21516612 has 24 divisors (see below), whose sum is σ = 54067776. Its totient is φ = 6620448.

The previous prime is 21516589. The next prime is 21516613. The reversal of 21516612 is 21661512.

It is not an unprimeable number, because it can be changed into a prime (21516613) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68808 + ... + 69119.

It is an arithmetic number, because the mean of its divisors is an integer number (2252824).

Almost surely, 2^21516612 is an apocalyptic number.

It is an amenable number.

21516612 is an abundant number, since it is smaller than the sum of its proper divisors (32551164).

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

21516612 is a wasteful number, since it uses less digits than its factorization.

21516612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137947 (or 137945 counting only the distinct ones).

The product of its digits is 720, while the sum is 24.

The square root of 21516612 is about 4638.6002198939. The cubic root of 21516612 is about 278.1364856091.

The spelling of 21516612 in words is "twenty-one million, five hundred sixteen thousand, six hundred twelve".