21089924 has 12 divisors (see below), whose sum is σ = 38850000. Its totient is φ = 9989928.

The previous prime is 21089921. The next prime is 21089947. The reversal of 21089924 is 42998012.

It is not an unprimeable number, because it can be changed into a prime (21089921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138674 + ... + 138825.

It is an arithmetic number, because the mean of its divisors is an integer number (3237500).

Almost surely, 2^21089924 is an apocalyptic number.

It is an amenable number.

21089924 is a deficient number, since it is larger than the sum of its proper divisors (17760076).

21089924 is a wasteful number, since it uses less digits than its factorization.

21089924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277522 (or 277520 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 21089924 is about 4592.3767267070. The cubic root of 21089924 is about 276.2856560789.

The spelling of 21089924 in words is "twenty-one million, eighty-nine thousand, nine hundred twenty-four".