21620880 has 60 divisors (see below), whose sum is σ = 72612540. Its totient is φ = 5765376.

The previous prime is 21620869. The next prime is 21620881. The reversal of 21620880 is 8802612.

It can be written as a sum of positive squares in 2 ways, for example, as 16257024 + 5363856 = 4032^2 + 2316^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is not an unprimeable number, because it can be changed into a prime (21620881) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14295 + ... + 15734.

It is an arithmetic number, because the mean of its divisors is an integer number (1210209).

Almost surely, 2^21620880 is an apocalyptic number.

21620880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21620880 is an abundant number, since it is smaller than the sum of its proper divisors (50991660).

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

21620880 is a wasteful number, since it uses less digits than its factorization.

21620880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30048 (or 30039 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21620880 is about 4649.8258031888. The cubic root of 21620880 is about 278.5850385010.

It can be divided in two parts, 21620 and 880, that added together give a square (22500 = 150²).

The spelling of 21620880 in words is "twenty-one million, six hundred twenty thousand, eight hundred eighty".