21667890 has 32 divisors (see below), whose sum is σ = 52140096. Its totient is φ = 5762880.

The previous prime is 21667879. The next prime is 21667913. The reversal of 21667890 is 9876612.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15000 + ... + 16380.

It is an arithmetic number, because the mean of its divisors is an integer number (1629378).

Almost surely, 2^21667890 is an apocalyptic number.

21667890 is an abundant number, since it is smaller than the sum of its proper divisors (30472206).

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

21667890 is a wasteful number, since it uses less digits than its factorization.

21667890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1914.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21667890 is about 4654.8780864809. The cubic root of 21667890 is about 278.7868002920.

The spelling of 21667890 in words is "twenty-one million, six hundred sixty-seven thousand, eight hundred ninety".