21356612 has 18 divisors (see below), whose sum is σ = 38201982. Its totient is φ = 10446784.

The previous prime is 21356611. The next prime is 21356633. The reversal of 21356612 is 21665312.

It can be written as a sum of positive squares in only one way, i.e., 21215236 + 141376 = 4606^2 + 376^2 .

It is a super-2 number, since 2×21356612² = 912209752237088, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21356611) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7628 + ... + 10044.

Almost surely, 2^21356612 is an apocalyptic number.

It is an amenable number.

21356612 is a deficient number, since it is larger than the sum of its proper divisors (16845370).

21356612 is a wasteful number, since it uses less digits than its factorization.

21356612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2515 (or 2466 counting only the distinct ones).

The product of its digits is 2160, while the sum is 26.

The square root of 21356612 is about 4621.3214560340. The cubic root of 21356612 is about 277.4453513575.

The spelling of 21356612 in words is "twenty-one million, three hundred fifty-six thousand, six hundred twelve".