21905394 has 16 divisors (see below), whose sum is σ = 50069568. Its totient is φ = 6258672.

The previous prime is 21905383. The next prime is 21905399. The reversal of 21905394 is 49350912.

It is not an unprimeable number, because it can be changed into a prime (21905399) 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, 260737 + ... + 260820.

It is an arithmetic number, because the mean of its divisors is an integer number (3129348).

Almost surely, 2^21905394 is an apocalyptic number.

21905394 is an abundant number, since it is smaller than the sum of its proper divisors (28164174).

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

21905394 is a wasteful number, since it uses less digits than its factorization.

21905394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521569.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 21905394 is about 4680.3198608642. The cubic root of 21905394 is about 279.8017048392.

The spelling of 21905394 in words is "twenty-one million, nine hundred five thousand, three hundred ninety-four".