21956890 has 16 divisors (see below), whose sum is σ = 39575808. Its totient is φ = 8770896.

The previous prime is 21956887. The next prime is 21956941. The reversal of 21956890 is 9865912.

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 in 7 ways as a sum of consecutive naturals, for example, 13459 + ... + 15001.

It is an arithmetic number, because the mean of its divisors is an integer number (2473488).

Almost surely, 2^21956890 is an apocalyptic number.

21956890 is a deficient number, since it is larger than the sum of its proper divisors (17618918).

21956890 is a wasteful number, since it uses less digits than its factorization.

21956890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2973.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 21956890 is about 4685.8179648808. The cubic root of 21956890 is about 280.0207892727.

The spelling of 21956890 in words is "twenty-one million, nine hundred fifty-six thousand, eight hundred ninety".