19624765981 has 2 divisors, whose sum is σ = 19624765982. Its totient is φ = 19624765980.

The previous prime is 19624765921. The next prime is 19624765991. The reversal of 19624765981 is 18956742691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19441840356 + 182925625 = 139434^2 + 13525^2 .

It is a cyclic number.

It is not a de Polignac number, because 19624765981 - 2⁹ = 19624765469 is a prime.

It is a super-2 number, since 2×19624765981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19624765921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9812382990 + 9812382991.

It is an arithmetic number, because the mean of its divisors is an integer number (9812382991).

Almost surely, 2^19624765981 is an apocalyptic number.

It is an amenable number.

19624765981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19624765981 is an equidigital number, since it uses as much as digits as its factorization.

19624765981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6531840, while the sum is 58.

The spelling of 19624765981 in words is "nineteen billion, six hundred twenty-four million, seven hundred sixty-five thousand, nine hundred eighty-one".