21662890 has 8 divisors (see below), whose sum is σ = 38993220. Its totient is φ = 8665152.

The previous prime is 21662833. The next prime is 21662897. The reversal of 21662890 is 9826612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20985561 + 677329 = 4581^2 + 823^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21662897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1083135 + ... + 1083154.

Almost surely, 2^21662890 is an apocalyptic number.

21662890 is a deficient number, since it is larger than the sum of its proper divisors (17330330).

21662890 is a wasteful number, since it uses less digits than its factorization.

21662890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2166296.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 21662890 is about 4654.3409845004. The cubic root of 21662890 is about 278.7653547147.

The spelling of 21662890 in words is "twenty-one million, six hundred sixty-two thousand, eight hundred ninety".