21910646987 has 2 divisors, whose sum is σ = 21910646988. Its totient is φ = 21910646986.

The previous prime is 21910646981. The next prime is 21910647001. The reversal of 21910646987 is 78964601912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21910646987 - 2¹² = 21910642891 is a prime.

It is not a weakly prime, because it can be changed into another prime (21910646981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10955323493 + 10955323494.

It is an arithmetic number, because the mean of its divisors is an integer number (10955323494).

Almost surely, 2^21910646987 is an apocalyptic number.

21910646987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21910646987 is an equidigital number, since it uses as much as digits as its factorization.

21910646987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1306368, while the sum is 53.

The spelling of 21910646987 in words is "twenty-one billion, nine hundred ten million, six hundred forty-six thousand, nine hundred eighty-seven".