21264628 has 48 divisors (see below), whose sum is σ = 47376000. Its totient is φ = 8279040.

The previous prime is 21264613. The next prime is 21264689. The reversal of 21264628 is 82646212.

It is a self number, because there is not a number n which added to its sum of digits gives 21264628.

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, 14388 + ... + 15796.

It is an arithmetic number, because the mean of its divisors is an integer number (987000).

Almost surely, 2^21264628 is an apocalyptic number.

21264628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21264628, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23688000).

21264628 is an abundant number, since it is smaller than the sum of its proper divisors (26111372).

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

21264628 is a wasteful number, since it uses less digits than its factorization.

21264628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1445 (or 1429 counting only the distinct ones).

The product of its digits is 9216, while the sum is 31.

The square root of 21264628 is about 4611.3585850593. The cubic root of 21264628 is about 277.0464544331.

The spelling of 21264628 in words is "twenty-one million, two hundred sixty-four thousand, six hundred twenty-eight".