1721234861 has 2 divisors, whose sum is σ = 1721234862. Its totient is φ = 1721234860.

The previous prime is 1721234843. The next prime is 1721234869. The reversal of 1721234861 is 1684321271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1557880900 + 163353961 = 39470^2 + 12781^2 .

It is an emirp because it is prime and its reverse (1684321271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1721234861 - 2¹⁰ = 1721233837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1721234869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860617430 + 860617431.

It is an arithmetic number, because the mean of its divisors is an integer number (860617431).

Almost surely, 2^1721234861 is an apocalyptic number.

It is an amenable number.

1721234861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721234861 is an equidigital number, since it uses as much as digits as its factorization.

1721234861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 35.

The square root of 1721234861 is about 41487.7676068501. The cubic root of 1721234861 is about 1198.4319475038.

The spelling of 1721234861 in words is "one billion, seven hundred twenty-one million, two hundred thirty-four thousand, eight hundred sixty-one".