21662120 has 32 divisors (see below), whose sum is σ = 49005000. Its totient is φ = 8617728.

The previous prime is 21662117. The next prime is 21662129. The reversal of 21662120 is 2126612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 18992164 + 2669956 = 4358^2 + 1634^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21662092 and 21662101.

It is not an unprimeable number, because it can be changed into a prime (21662129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6506 + ... + 9254.

Almost surely, 2^21662120 is an apocalyptic number.

21662120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21662120 is an abundant number, since it is smaller than the sum of its proper divisors (27342880).

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

21662120 is a wasteful number, since it uses less digits than its factorization.

21662120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2957 (or 2953 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21662120 is about 4654.2582652878. The cubic root of 21662120 is about 278.7620518025.

Adding to 21662120 its reverse (2126612), we get a palindrome (23788732).

The spelling of 21662120 in words is "twenty-one million, six hundred sixty-two thousand, one hundred twenty".