21609732 has 12 divisors (see below), whose sum is σ = 50422736. Its totient is φ = 7203240.

The previous prime is 21609713. The next prime is 21609733. The reversal of 21609732 is 23790612.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21609732² = 933961034223648, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21609732.

It is not an unprimeable number, because it can be changed into a prime (21609733) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 900394 + ... + 900417.

Almost surely, 2^21609732 is an apocalyptic number.

It is an amenable number.

21609732 is an abundant number, since it is smaller than the sum of its proper divisors (28813004).

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

21609732 is a wasteful number, since it uses less digits than its factorization.

21609732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800818 (or 1800816 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 30.

The square root of 21609732 is about 4648.6268940409. The cubic root of 21609732 is about 278.5371496094.

The spelling of 21609732 in words is "twenty-one million, six hundred nine thousand, seven hundred thirty-two".