21015007087 has 2 divisors, whose sum is σ = 21015007088. Its totient is φ = 21015007086.

The previous prime is 21015007081. The next prime is 21015007121. The reversal of 21015007087 is 78070051012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21015007087 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21015007081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10507503543 + 10507503544.

It is an arithmetic number, because the mean of its divisors is an integer number (10507503544).

Almost surely, 2^21015007087 is an apocalyptic number.

21015007087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21015007087 is an equidigital number, since it uses as much as digits as its factorization.

21015007087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3920, while the sum is 31.

Adding to 21015007087 its reverse (78070051012), we get a palindrome (99085058099).

The spelling of 21015007087 in words is "twenty-one billion, fifteen million, seven thousand, eighty-seven".