21322578 has 16 divisors (see below), whose sum is σ = 43246656. Its totient is φ = 7007280.

The previous prime is 21322571. The next prime is 21322601. The reversal of 21322578 is 87522312.

It is not an unprimeable number, because it can be changed into a prime (21322571) 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, 24601 + ... + 25452.

It is an arithmetic number, because the mean of its divisors is an integer number (2702916).

Almost surely, 2^21322578 is an apocalyptic number.

21322578 is an abundant number, since it is smaller than the sum of its proper divisors (21924078).

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

21322578 is a wasteful number, since it uses less digits than its factorization.

21322578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50129.

The product of its digits is 6720, while the sum is 30.

The square root of 21322578 is about 4617.6377077462. The cubic root of 21322578 is about 277.2978935828.

It can be divided in two parts, 213 and 22578, that added together give a triangular number (22791 = T₂₁₃).

The spelling of 21322578 in words is "twenty-one million, three hundred twenty-two thousand, five hundred seventy-eight".