21813572 has 24 divisors (see below), whose sum is σ = 42772800. Its totient is φ = 9646560.

The previous prime is 21813569. The next prime is 21813619. The reversal of 21813572 is 27531812.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5072 + ... + 8327.

It is an arithmetic number, because the mean of its divisors is an integer number (1782200).

Almost surely, 2^21813572 is an apocalyptic number.

21813572 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21813572 is a deficient number, since it is larger than the sum of its proper divisors (20959228).

21813572 is a wasteful number, since it uses less digits than its factorization.

21813572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13451 (or 13449 counting only the distinct ones).

The product of its digits is 3360, while the sum is 29.

The square root of 21813572 is about 4670.5001873461. The cubic root of 21813572 is about 279.4102040962.

The spelling of 21813572 in words is "twenty-one million, eight hundred thirteen thousand, five hundred seventy-two".