15632021681 has 2 divisors, whose sum is σ = 15632021682. Its totient is φ = 15632021680.

The previous prime is 15632021651. The next prime is 15632021693. The reversal of 15632021681 is 18612023651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15379720225 + 252301456 = 124015^2 + 15884^2 .

It is a cyclic number.

It is not a de Polignac number, because 15632021681 - 2¹⁴ = 15632005297 is a prime.

It is a super-2 number, since 2×15632021681² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (15632021651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7816010840 + 7816010841.

It is an arithmetic number, because the mean of its divisors is an integer number (7816010841).

Almost surely, 2^15632021681 is an apocalyptic number.

It is an amenable number.

15632021681 is a deficient number, since it is larger than the sum of its proper divisors (1).

15632021681 is an equidigital number, since it uses as much as digits as its factorization.

15632021681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The spelling of 15632021681 in words is "fifteen billion, six hundred thirty-two million, twenty-one thousand, six hundred eighty-one".