21620180 has 24 divisors (see below), whose sum is σ = 45709440. Its totient is φ = 8589600.

The previous prime is 21620153. The next prime is 21620189. The reversal of 21620180 is 8102612.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21620189) 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 7 ways as a sum of consecutive naturals, for example, 560 + ... + 6599.

It is an arithmetic number, because the mean of its divisors is an integer number (1904560).

Almost surely, 2^21620180 is an apocalyptic number.

21620180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21620180 is an abundant number, since it is smaller than the sum of its proper divisors (24089260).

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

21620180 is a wasteful number, since it uses less digits than its factorization.

21620180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7319 (or 7317 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21620180 is about 4649.7505309425. The cubic root of 21620180 is about 278.5820319686.

Adding to 21620180 its reverse (8102612), we get a palindrome (29722792).

The spelling of 21620180 in words is "twenty-one million, six hundred twenty thousand, one hundred eighty".