1251535121 has 4 divisors (see below), whose sum is σ = 1325154852. Its totient is φ = 1177915392.

The previous prime is 1251535091. The next prime is 1251535123. The reversal of 1251535121 is 1215351521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1055535121 + 196000000 = 32489^2 + 14000^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251535121 - 2¹⁸ = 1251272977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1251535123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36809840 + ... + 36809873.

It is an arithmetic number, because the mean of its divisors is an integer number (331288713).

Almost surely, 2^1251535121 is an apocalyptic number.

It is an amenable number.

1251535121 is a deficient number, since it is larger than the sum of its proper divisors (73619731).

1251535121 is an equidigital number, since it uses as much as digits as its factorization.

1251535121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73619730.

The product of its digits is 1500, while the sum is 26.

The square root of 1251535121 is about 35377.0422873366. The cubic root of 1251535121 is about 1077.6581403435.

Adding to 1251535121 its reverse (1215351521), we get a palindrome (2466886642).

The spelling of 1251535121 in words is "one billion, two hundred fifty-one million, five hundred thirty-five thousand, one hundred twenty-one".