21620890 has 8 divisors (see below), whose sum is σ = 38917620. Its totient is φ = 8648352.

The previous prime is 21620881. The next prime is 21620891. The reversal of 21620890 is 9802612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20259001 + 1361889 = 4501^2 + 1167^2 .

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 (21620891) 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, 1081035 + ... + 1081054.

Almost surely, 2^21620890 is an apocalyptic number.

21620890 is a deficient number, since it is larger than the sum of its proper divisors (17296730).

21620890 is a wasteful number, since it uses less digits than its factorization.

21620890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2162096.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21620890 is about 4649.8268784977. The cubic root of 21620890 is about 278.5850814510.

The spelling of 21620890 in words is "twenty-one million, six hundred twenty thousand, eight hundred ninety".