21356516 has 24 divisors (see below), whose sum is σ = 38243520. Its totient is φ = 10432800.

The previous prime is 21356507. The next prime is 21356549. The reversal of 21356516 is 61565312.

It is a super-2 number, since 2×21356516² = 912201551316512, which contains 22 as substring.

It is a plaindrome in base 13.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39206 + ... + 39746.

It is an arithmetic number, because the mean of its divisors is an integer number (1593480).

Almost surely, 2^21356516 is an apocalyptic number.

It is an amenable number.

21356516 is a deficient number, since it is larger than the sum of its proper divisors (16887004).

21356516 is a wasteful number, since it uses less digits than its factorization.

21356516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755 (or 753 counting only the distinct ones).

The product of its digits is 5400, while the sum is 29.

The square root of 21356516 is about 4621.3110693828. The cubic root of 21356516 is about 277.4449356425. Note that the first 3 decimals are identical.

The spelling of 21356516 in words is "twenty-one million, three hundred fifty-six thousand, five hundred sixteen".