21430872 has 64 divisors (see below), whose sum is σ = 60825600. Its totient is φ = 6988320.

The previous prime is 21430861. The next prime is 21430909. The reversal of 21430872 is 27803412.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 9097 + ... + 11207.

It is an arithmetic number, because the mean of its divisors is an integer number (950400).

Almost surely, 2^21430872 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 21430872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30412800).

21430872 is an abundant number, since it is smaller than the sum of its proper divisors (39394728).

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

21430872 is a wasteful number, since it uses less digits than its factorization.

21430872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2173 (or 2163 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21430872 is about 4629.3489823084. The cubic root of 21430872 is about 277.7665517715.

The spelling of 21430872 in words is "twenty-one million, four hundred thirty thousand, eight hundred seventy-two".