21662240 has 24 divisors (see below), whose sum is σ = 51177420. Its totient is φ = 8664832.

The previous prime is 21662237. The next prime is 21662281. The reversal of 21662240 is 4226612.

It can be written as a sum of positive squares in 2 ways, for example, as 21492496 + 169744 = 4636^2 + 412^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67535 + ... + 67854.

Almost surely, 2^21662240 is an apocalyptic number.

21662240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21662240 is an abundant number, since it is smaller than the sum of its proper divisors (29515180).

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

21662240 is a wasteful number, since it uses less digits than its factorization.

21662240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135404 (or 135396 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 21662240 is about 4654.2711566904. The cubic root of 21662240 is about 278.7625665472.

Adding to 21662240 its reverse (4226612), we get a palindrome (25888852).

The spelling of 21662240 in words is "twenty-one million, six hundred sixty-two thousand, two hundred forty".