21616587 has 12 divisors (see below), whose sum is σ = 31575960. Its totient is φ = 14248608.

The previous prime is 21616583. The next prime is 21616591. The reversal of 21616587 is 78561612.

It is an interprime number because it is at equal distance from previous prime (21616583) and next prime (21616591).

It is not a de Polignac number, because 21616587 - 2² = 21616583 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21616583) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12693 + ... + 14294.

It is an arithmetic number, because the mean of its divisors is an integer number (2631330).

Almost surely, 2^21616587 is an apocalyptic number.

21616587 is a deficient number, since it is larger than the sum of its proper divisors (9959373).

21616587 is a wasteful number, since it uses less digits than its factorization.

21616587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27082 (or 27079 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21616587 is about 4649.3641500747. The cubic root of 21616587 is about 278.5665988455.

The spelling of 21616587 in words is "twenty-one million, six hundred sixteen thousand, five hundred eighty-seven".