21315787587 has 12 divisors (see below), whose sum is σ = 30810975624. Its totient is φ = 14200599840.

The previous prime is 21315787547. The next prime is 21315787607. The reversal of 21315787587 is 78578751312.

21315787587 is a `hidden beast` number, since 2 + 1 + 3 + 1 + 57 + 8 + 7 + 587 = 666.

It is not a de Polignac number, because 21315787587 - 2⁷ = 21315787459 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21315787517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 813489 + ... + 839282.

It is an arithmetic number, because the mean of its divisors is an integer number (2567581302).

Almost surely, 2^21315787587 is an apocalyptic number.

21315787587 is a deficient number, since it is larger than the sum of its proper divisors (9495188037).

21315787587 is a wasteful number, since it uses less digits than its factorization.

21315787587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1654210 (or 1654207 counting only the distinct ones).

The product of its digits is 3292800, while the sum is 54.

The spelling of 21315787587 in words is "twenty-one billion, three hundred fifteen million, seven hundred eighty-seven thousand, five hundred eighty-seven".