21091702087 has 2 divisors, whose sum is σ = 21091702088. Its totient is φ = 21091702086.

The previous prime is 21091702081. The next prime is 21091702123. The reversal of 21091702087 is 78020719012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21091702087 - 2¹⁹ = 21091177799 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21091702081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10545851043 + 10545851044.

It is an arithmetic number, because the mean of its divisors is an integer number (10545851044).

Almost surely, 2^21091702087 is an apocalyptic number.

21091702087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21091702087 is an equidigital number, since it uses as much as digits as its factorization.

21091702087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14112, while the sum is 37.

The spelling of 21091702087 in words is "twenty-one billion, ninety-one million, seven hundred two thousand, eighty-seven".