21442939 has 12 divisors (see below), whose sum is σ = 25526424. Its totient is φ = 17950464.

The previous prime is 21442937. The next prime is 21442957. The reversal of 21442939 is 93924412.

It is not a de Polignac number, because 21442939 - 2¹ = 21442937 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21442937) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2982 + ... + 7195.

It is an arithmetic number, because the mean of its divisors is an integer number (2127202).

Almost surely, 2^21442939 is an apocalyptic number.

21442939 is a deficient number, since it is larger than the sum of its proper divisors (4083485).

21442939 is a wasteful number, since it uses less digits than its factorization.

21442939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10234 (or 10227 counting only the distinct ones).

The product of its digits is 15552, while the sum is 34.

The square root of 21442939 is about 4630.6521139036. The cubic root of 21442939 is about 277.8186756434.

The spelling of 21442939 in words is "twenty-one million, four hundred forty-two thousand, nine hundred thirty-nine".