21684026 has 32 divisors (see below), whose sum is σ = 40268928. Its totient is φ = 8527680.

The previous prime is 21684023. The next prime is 21684029. The reversal of 21684026 is 62048612.

It is an interprime number because it is at equal distance from previous prime (21684023) and next prime (21684029).

It is a self number, because there is not a number n which added to its sum of digits gives 21684026.

It is not an unprimeable number, because it can be changed into a prime (21684023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51296 + ... + 51716.

It is an arithmetic number, because the mean of its divisors is an integer number (1258404).

Almost surely, 2^21684026 is an apocalyptic number.

21684026 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21684026 is a deficient number, since it is larger than the sum of its proper divisors (18584902).

21684026 is a wasteful number, since it uses less digits than its factorization.

21684026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 726.

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 21684026 is about 4656.6109994287. The cubic root of 21684026 is about 278.8559869641.

The spelling of 21684026 in words is "twenty-one million, six hundred eighty-four thousand, twenty-six".