21313991087 has 2 divisors, whose sum is σ = 21313991088. Its totient is φ = 21313991086.

The previous prime is 21313991053. The next prime is 21313991093. The reversal of 21313991087 is 78019931312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21313991087 - 2¹⁶ = 21313925551 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21313991687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656995543 + 10656995544.

It is an arithmetic number, because the mean of its divisors is an integer number (10656995544).

Almost surely, 2^21313991087 is an apocalyptic number.

21313991087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313991087 is an equidigital number, since it uses as much as digits as its factorization.

21313991087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 44.

The spelling of 21313991087 in words is "twenty-one billion, three hundred thirteen million, nine hundred ninety-one thousand, eighty-seven".