21790863187 has 2 divisors, whose sum is σ = 21790863188. Its totient is φ = 21790863186.

The previous prime is 21790863103. The next prime is 21790863197. The reversal of 21790863187 is 78136809712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21790863187 - 2¹⁵ = 21790830419 is a prime.

It is not a weakly prime, because it can be changed into another prime (21790863197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10895431593 + 10895431594.

It is an arithmetic number, because the mean of its divisors is an integer number (10895431594).

Almost surely, 2^21790863187 is an apocalyptic number.

21790863187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21790863187 is an equidigital number, since it uses as much as digits as its factorization.

21790863187 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1016064, while the sum is 52.

The spelling of 21790863187 in words is "twenty-one billion, seven hundred ninety million, eight hundred sixty-three thousand, one hundred eighty-seven".