21564426 has 16 divisors (see below), whose sum is σ = 46446624. Its totient is φ = 6635184.

The previous prime is 21564407. The next prime is 21564427. The reversal of 21564426 is 62446512.

It is a junction number, because it is equal to n+sod(n) for n = 21564393 and 21564402.

It is not an unprimeable number, because it can be changed into a prime (21564427) 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, 138156 + ... + 138311.

It is an arithmetic number, because the mean of its divisors is an integer number (2902914).

Almost surely, 2^21564426 is an apocalyptic number.

21564426 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21564426 is an abundant number, since it is smaller than the sum of its proper divisors (24882198).

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

21564426 is a wasteful number, since it uses less digits than its factorization.

21564426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 276485.

The product of its digits is 11520, while the sum is 30.

The square root of 21564426 is about 4643.7512853296. The cubic root of 21564426 is about 278.3423572279.

The spelling of 21564426 in words is "twenty-one million, five hundred sixty-four thousand, four hundred twenty-six".