21957838 has 16 divisors (see below), whose sum is σ = 37709280. Its totient is φ = 9393696.

The previous prime is 21957811. The next prime is 21957841. The reversal of 21957838 is 83875912.

It is a junction number, because it is equal to n+sod(n) for n = 21957794 and 21957803.

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 7 ways as a sum of consecutive naturals, for example, 9808 + ... + 11836.

It is an arithmetic number, because the mean of its divisors is an integer number (2356830).

Almost surely, 2^21957838 is an apocalyptic number.

21957838 is a deficient number, since it is larger than the sum of its proper divisors (15751442).

21957838 is a wasteful number, since it uses less digits than its factorization.

21957838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2811.

The product of its digits is 120960, while the sum is 43.

The square root of 21957838 is about 4685.9191200873. The cubic root of 21957838 is about 280.0248192285.

The spelling of 21957838 in words is "twenty-one million, nine hundred fifty-seven thousand, eight hundred thirty-eight".