21732220 has 12 divisors (see below), whose sum is σ = 45637704. Its totient is φ = 8692880.

The previous prime is 21732203. The next prime is 21732229. The reversal of 21732220 is 2223712.

It is a super-2 number, since 2×21732220² = 944578772256800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21732229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 543286 + ... + 543325.

It is an arithmetic number, because the mean of its divisors is an integer number (3803142).

Almost surely, 2^21732220 is an apocalyptic number.

21732220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21732220 is an abundant number, since it is smaller than the sum of its proper divisors (23905484).

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

21732220 is a wasteful number, since it uses less digits than its factorization.

21732220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1086620 (or 1086618 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 21732220 is about 4661.7829207289. The cubic root of 21732220 is about 279.0624252773.

Adding to 21732220 its reverse (2223712), we get a palindrome (23955932).

It can be divided in two parts, 21732 and 220, that added together give a cube (21952 = 28³).

The spelling of 21732220 in words is "twenty-one million, seven hundred thirty-two thousand, two hundred twenty".