1234125721 has 4 divisors (see below), whose sum is σ = 1234200244. Its totient is φ = 1234051200.

The previous prime is 1234125719. The next prime is 1234125731. The reversal of 1234125721 is 1275214321.

1234125721 is a nontrivial binomial coefficient, being equal to C(49682, 2).

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1275214321 = 43 ⋅29656147.

It can be written as a sum of positive squares in 2 ways, for example, as 471758400 + 762367321 = 21720^2 + 27611^2 .

It is a 3-Lehmer number, since φ(1234125721) divides (1234125721-1)³.

It is a cyclic number.

It is not a de Polignac number, because 1234125721 - 2¹ = 1234125719 is a prime.

It is a deceptive number, since it divides R_1234125720.

It is a self number, because there is not a number n which added to its sum of digits gives 1234125721.

It is not an unprimeable number, because it can be changed into a prime (1234125701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 49681.

It is an arithmetic number, because the mean of its divisors is an integer number (308550061).

It is a Poulet number, since it divides 2^1234125720-1.

Almost surely, 2^1234125721 is an apocalyptic number.

1234125721 is the 49681-st triangular number and also the 24841-st hexagonal number.

1234125721 is the 16561-st centered nonagonal number.

It is an amenable number.

1234125721 is a deficient number, since it is larger than the sum of its proper divisors (74523).

1234125721 is an equidigital number, since it uses as much as digits as its factorization.

1234125721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74522.

The product of its digits is 3360, while the sum is 28.

The square root of 1234125721 is about 35130.1255477404. The cubic root of 1234125721 is about 1072.6378915045.

The spelling of 1234125721 in words is "one billion, two hundred thirty-four million, one hundred twenty-five thousand, seven hundred twenty-one".