21621608 has 8 divisors (see below), whose sum is σ = 40540530. Its totient is φ = 10810800.

The previous prime is 21621577. The next prime is 21621629. The reversal of 21621608 is 80612612.

It can be written as a sum of positive squares in only one way, i.e., 19377604 + 2244004 = 4402^2 + 1498^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1351343 + ... + 1351358.

Almost surely, 2^21621608 is an apocalyptic number.

It is an amenable number.

21621608 is a deficient number, since it is larger than the sum of its proper divisors (18918922).

21621608 is a wasteful number, since it uses less digits than its factorization.

21621608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2702707 (or 2702703 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21621608 is about 4649.9040850323. The cubic root of 21621608 is about 278.5881652259.

The spelling of 21621608 in words is "twenty-one million, six hundred twenty-one thousand, six hundred eight".