21516906 has 32 divisors (see below), whose sum is σ = 44673408. Its totient is φ = 6903360.

The previous prime is 21516893. The next prime is 21516919. The reversal of 21516906 is 60961512.

It is an interprime number because it is at equal distance from previous prime (21516893) and next prime (21516919).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22396 + ... + 23336.

It is an arithmetic number, because the mean of its divisors is an integer number (1396044).

Almost surely, 2^21516906 is an apocalyptic number.

21516906 is an abundant number, since it is smaller than the sum of its proper divisors (23156502).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21516906 is a wasteful number, since it uses less digits than its factorization.

21516906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1086.

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 21516906 is about 4638.6319103805. The cubic root of 21516906 is about 278.1377524094.

It can be divided in two parts, 21516 and 906, that added together give a palindrome (22422).

The spelling of 21516906 in words is "twenty-one million, five hundred sixteen thousand, nine hundred six".