21860720641 has 2 divisors, whose sum is σ = 21860720642. Its totient is φ = 21860720640.

The previous prime is 21860720633. The next prime is 21860720677. The reversal of 21860720641 is 14602706812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16901040016 + 4959680625 = 130004^2 + 70425^2 .

It is a cyclic number.

It is not a de Polignac number, because 21860720641 - 2³ = 21860720633 is a prime.

It is a super-2 number, since 2×21860720641² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21860720641.

It is not a weakly prime, because it can be changed into another prime (21860720741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10930360320 + 10930360321.

It is an arithmetic number, because the mean of its divisors is an integer number (10930360321).

Almost surely, 2^21860720641 is an apocalyptic number.

It is an amenable number.

21860720641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21860720641 is an equidigital number, since it uses as much as digits as its factorization.

21860720641 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32256, while the sum is 37.

The spelling of 21860720641 in words is "twenty-one billion, eight hundred sixty million, seven hundred twenty thousand, six hundred forty-one".