21890887 has 4 divisors (see below), whose sum is σ = 22249816. Its totient is φ = 21531960.

The previous prime is 21890879. The next prime is 21890893. The reversal of 21890887 is 78809812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21890887 - 2³ = 21890879 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21890807) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 179373 + ... + 179494.

It is an arithmetic number, because the mean of its divisors is an integer number (5562454).

Almost surely, 2^21890887 is an apocalyptic number.

21890887 is a deficient number, since it is larger than the sum of its proper divisors (358929).

21890887 is an equidigital number, since it uses as much as digits as its factorization.

21890887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358928.

The product of its (nonzero) digits is 64512, while the sum is 43.

The square root of 21890887 is about 4678.7698169498. The cubic root of 21890887 is about 279.7399243220.

The spelling of 21890887 in words is "twenty-one million, eight hundred ninety thousand, eight hundred eighty-seven".