21145620 has 48 divisors (see below), whose sum is σ = 62693568. Its totient is φ = 5306880.

The previous prime is 21145601. The next prime is 21145639. The reversal of 21145620 is 2654112.

It is an interprime number because it is at equal distance from previous prime (21145601) and next prime (21145639).

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, 9346 + ... + 11385.

It is an arithmetic number, because the mean of its divisors is an integer number (1306116).

Almost surely, 2^21145620 is an apocalyptic number.

21145620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21145620 is an abundant number, since it is smaller than the sum of its proper divisors (41547948).

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

21145620 is a wasteful number, since it uses less digits than its factorization.

21145620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20760 (or 20758 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21145620 is about 4598.4366908766. The cubic root of 21145620 is about 276.5286548962.

Adding to 21145620 its reverse (2654112), we get a palindrome (23799732).

The spelling of 21145620 in words is "twenty-one million, one hundred forty-five thousand, six hundred twenty".