21051502687 has 2 divisors, whose sum is σ = 21051502688. Its totient is φ = 21051502686.

The previous prime is 21051502631. The next prime is 21051502691. The reversal of 21051502687 is 78620515012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21051502687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21051532687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525751343 + 10525751344.

It is an arithmetic number, because the mean of its divisors is an integer number (10525751344).

Almost surely, 2^21051502687 is an apocalyptic number.

21051502687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21051502687 is an equidigital number, since it uses as much as digits as its factorization.

21051502687 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 33600, while the sum is 37.

The spelling of 21051502687 in words is "twenty-one billion, fifty-one million, five hundred two thousand, six hundred eighty-seven".