21940810 has 16 divisors (see below), whose sum is σ = 39613536. Its totient is φ = 8749648.

The previous prime is 21940799. The next prime is 21940813. The reversal of 21940810 is 1804912.

It is a happy number.

It is a super-2 number, since 2×21940810² = 962798286912200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21940813) 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, 309 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (2475846).

Almost surely, 2^21940810 is an apocalyptic number.

21940810 is a deficient number, since it is larger than the sum of its proper divisors (17672726).

21940810 is a wasteful number, since it uses less digits than its factorization.

21940810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6677.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21940810 is about 4684.1018349306. The cubic root of 21940810 is about 279.9524153831.

The spelling of 21940810 in words is "twenty-one million, nine hundred forty thousand, eight hundred ten".