21551712 has 96 divisors (see below), whose sum is σ = 69656832. Its totient is φ = 5681664.

The previous prime is 21551701. The next prime is 21551737. The reversal of 21551712 is 21715512.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7503 + ... + 9969.

It is an arithmetic number, because the mean of its divisors is an integer number (725592).

Almost surely, 2^21551712 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 21551712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34828416).

21551712 is an abundant number, since it is smaller than the sum of its proper divisors (48105120).

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

21551712 is a wasteful number, since it uses less digits than its factorization.

21551712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2500 (or 2492 counting only the distinct ones).

The product of its digits is 700, while the sum is 24.

The square root of 21551712 is about 4642.3821471309. The cubic root of 21551712 is about 278.2876445816.

The spelling of 21551712 in words is "twenty-one million, five hundred fifty-one thousand, seven hundred twelve".