21620830 has 64 divisors (see below), whose sum is σ = 49724928. Its totient is φ = 6572160.

The previous prime is 21620827. The next prime is 21620831. The reversal of 21620830 is 3802612.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21620831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 32784 + ... + 33436.

It is an arithmetic number, because the mean of its divisors is an integer number (776952).

Almost surely, 2^21620830 is an apocalyptic number.

21620830 is an abundant number, since it is smaller than the sum of its proper divisors (28104098).

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

21620830 is a wasteful number, since it uses less digits than its factorization.

21620830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21620830 is about 4649.8204266402. The cubic root of 21620830 is about 278.5848237509.

The spelling of 21620830 in words is "twenty-one million, six hundred twenty thousand, eight hundred thirty".