21153712 has 40 divisors (see below), whose sum is σ = 43965936. Its totient is φ = 9824256.

The previous prime is 21153703. The next prime is 21153757. The reversal of 21153712 is 21735112.

It is a happy number.

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, 22108 + ... + 23044.

Almost surely, 2^21153712 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21153712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21982968).

21153712 is an abundant number, since it is smaller than the sum of its proper divisors (22812224).

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

21153712 is a wasteful number, since it uses less digits than its factorization.

21153712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1045 (or 1039 counting only the distinct ones).

The product of its digits is 420, while the sum is 22.

The square root of 21153712 is about 4599.3164709552. The cubic root of 21153712 is about 276.5639243673.

Adding to 21153712 its reverse (21735112), we get a palindrome (42888824).

The spelling of 21153712 in words is "twenty-one million, one hundred fifty-three thousand, seven hundred twelve".