21906594 has 12 divisors (see below), whose sum is σ = 47464326. Its totient is φ = 7302192.

The previous prime is 21906593. The next prime is 21906607. The reversal of 21906594 is 49560912.

It can be written as a sum of positive squares in only one way, i.e., 21206025 + 700569 = 4605^2 + 837^2 .

It is not an unprimeable number, because it can be changed into a prime (21906593) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 608499 + ... + 608534.

Almost surely, 2^21906594 is an apocalyptic number.

21906594 is an abundant number, since it is smaller than the sum of its proper divisors (25557732).

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

21906594 is a wasteful number, since it uses less digits than its factorization.

21906594 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1217041 (or 1217038 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 21906594 is about 4680.4480554750. The cubic root of 21906594 is about 279.8068140209.

It can be divided in two parts, 21906 and 594, that added together give a square (22500 = 150²).

The spelling of 21906594 in words is "twenty-one million, nine hundred six thousand, five hundred ninety-four".