21440394 has 48 divisors (see below), whose sum is σ = 47803392. Its totient is φ = 6943104.

The previous prime is 21440389. The next prime is 21440399. The reversal of 21440394 is 49304412.

It is an interprime number because it is at equal distance from previous prime (21440389) and next prime (21440399).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440399) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 168759 + ... + 168885.

It is an arithmetic number, because the mean of its divisors is an integer number (995904).

Almost surely, 2^21440394 is an apocalyptic number.

21440394 is an abundant number, since it is smaller than the sum of its proper divisors (26362998).

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

21440394 is a wasteful number, since it uses less digits than its factorization.

21440394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331 (or 328 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21440394 is about 4630.3773064406. The cubic root of 21440394 is about 277.8076840453.

The spelling of 21440394 in words is "twenty-one million, four hundred forty thousand, three hundred ninety-four".