21877890 has 32 divisors (see below), whose sum is σ = 54319680. Its totient is φ = 5632704.

The previous prime is 21877883. The next prime is 21877897. The reversal of 21877890 is 9877812.

It is an interprime number because it is at equal distance from previous prime (21877883) and next prime (21877897).

It is not an unprimeable number, because it can be changed into a prime (21877897) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 11704 + ... + 13443.

It is an arithmetic number, because the mean of its divisors is an integer number (1697490).

Almost surely, 2^21877890 is an apocalyptic number.

21877890 is an abundant number, since it is smaller than the sum of its proper divisors (32441790).

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

21877890 is a wasteful number, since it uses less digits than its factorization.

21877890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25186.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 21877890 is about 4677.3806772594. The cubic root of 21877890 is about 279.6845512105.

The spelling of 21877890 in words is "twenty-one million, eight hundred seventy-seven thousand, eight hundred ninety".