21442940 has 12 divisors (see below), whose sum is σ = 45030216. Its totient is φ = 8577168.

The previous prime is 21442937. The next prime is 21442957. The reversal of 21442940 is 4924412.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 536054 + ... + 536093.

It is an arithmetic number, because the mean of its divisors is an integer number (3752518).

Almost surely, 2^21442940 is an apocalyptic number.

21442940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21442940 is an abundant number, since it is smaller than the sum of its proper divisors (23587276).

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

21442940 is a wasteful number, since it uses less digits than its factorization.

21442940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072156 (or 1072154 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21442940 is about 4630.6522218798. The cubic root of 21442940 is about 277.8186799621.

The spelling of 21442940 in words is "twenty-one million, four hundred forty-two thousand, nine hundred forty".