21561532 has 12 divisors (see below), whose sum is σ = 38535840. Its totient is φ = 10551296.

The previous prime is 21561503. The next prime is 21561571. The reversal of 21561532 is 23516512.

It is a junction number, because it is equal to n+sod(n) for n = 21561497 and 21561506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57157 + ... + 57532.

It is an arithmetic number, because the mean of its divisors is an integer number (3211320).

Almost surely, 2^21561532 is an apocalyptic number.

It is an amenable number.

21561532 is a deficient number, since it is larger than the sum of its proper divisors (16974308).

21561532 is a wasteful number, since it uses less digits than its factorization.

21561532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114740 (or 114738 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 21561532 is about 4643.4396733456. The cubic root of 21561532 is about 278.3299052570.

The spelling of 21561532 in words is "twenty-one million, five hundred sixty-one thousand, five hundred thirty-two".