21130887 has 16 divisors (see below), whose sum is σ = 28804608. Its totient is φ = 13776000.

The previous prime is 21130883. The next prime is 21130891. The reversal of 21130887 is 78803112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21130883) and next prime (21130891).

It is not a de Polignac number, because 21130887 - 2² = 21130883 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130883) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27762 + ... + 28512.

It is an arithmetic number, because the mean of its divisors is an integer number (1800288).

Almost surely, 2^21130887 is an apocalyptic number.

21130887 is a deficient number, since it is larger than the sum of its proper divisors (7673721).

21130887 is a wasteful number, since it uses less digits than its factorization.

21130887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 950.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 21130887 is about 4596.8344542739. The cubic root of 21130887 is about 276.4644171134.

Adding to 21130887 its reverse (78803112), we get a palindrome (99933999).

The spelling of 21130887 in words is "twenty-one million, one hundred thirty thousand, eight hundred eighty-seven".