21317942 has 4 divisors (see below), whose sum is σ = 31976916. Its totient is φ = 10658970.

The previous prime is 21317927. The next prime is 21317951. The reversal of 21317942 is 24971312.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×21317942² = 908909302230728, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5329484 + ... + 5329487.

It is an arithmetic number, because the mean of its divisors is an integer number (7994229).

Almost surely, 2^21317942 is an apocalyptic number.

21317942 is a deficient number, since it is larger than the sum of its proper divisors (10658974).

21317942 is a wasteful number, since it uses less digits than its factorization.

21317942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10658973.

The product of its digits is 3024, while the sum is 29.

The square root of 21317942 is about 4617.1356921797. The cubic root of 21317942 is about 277.2777952279.

The spelling of 21317942 in words is "twenty-one million, three hundred seventeen thousand, nine hundred forty-two".