21757942 has 8 divisors (see below), whose sum is σ = 33084216. Its totient is φ = 10729872.

The previous prime is 21757873. The next prime is 21757951. The reversal of 21757942 is 24975712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74368 + ... + 74659.

It is an arithmetic number, because the mean of its divisors is an integer number (4135527).

Almost surely, 2^21757942 is an apocalyptic number.

21757942 is a deficient number, since it is larger than the sum of its proper divisors (11326274).

21757942 is a wasteful number, since it uses less digits than its factorization.

21757942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149102.

The product of its digits is 35280, while the sum is 37.

The square root of 21757942 is about 4664.5409206052. The cubic root of 21757942 is about 279.1724802037.

The spelling of 21757942 in words is "twenty-one million, seven hundred fifty-seven thousand, nine hundred forty-two".