21708438587 has 16 divisors (see below), whose sum is σ = 24246233088. Its totient is φ = 19265208480.

The previous prime is 21708438571. The next prime is 21708438589. The reversal of 21708438587 is 78583480712.

It is a cyclic number.

It is not a de Polignac number, because 21708438587 - 2⁴ = 21708438571 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21708438589) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 902438 + ... + 926180.

It is an arithmetic number, because the mean of its divisors is an integer number (1515389568).

Almost surely, 2^21708438587 is an apocalyptic number.

21708438587 is a deficient number, since it is larger than the sum of its proper divisors (2537794501).

21708438587 is a wasteful number, since it uses less digits than its factorization.

21708438587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25730.

The product of its (nonzero) digits is 3010560, while the sum is 53.

The spelling of 21708438587 in words is "twenty-one billion, seven hundred eight million, four hundred thirty-eight thousand, five hundred eighty-seven".