21621672 has 24 divisors (see below), whose sum is σ = 58558890. Its totient is φ = 7207200.

The previous prime is 21621643. The next prime is 21621683. The reversal of 21621672 is 27612612.

It can be written as a sum of positive squares in only one way, i.e., 20196036 + 1425636 = 4494^2 + 1194^2 .

It is a tau number, because it is divible by the number of its divisors (24).

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 in 5 ways as a sum of consecutive naturals, for example, 150079 + ... + 150222.

Almost surely, 2^21621672 is an apocalyptic number.

It is an amenable number.

21621672 is an abundant number, since it is smaller than the sum of its proper divisors (36937218).

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

21621672 is a wasteful number, since it uses less digits than its factorization.

21621672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300313 (or 300306 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 21621672 is about 4649.9109668896. The cubic root of 21621672 is about 278.5884400995.

The spelling of 21621672 in words is "twenty-one million, six hundred twenty-one thousand, six hundred seventy-two".