21878087 has 8 divisors (see below), whose sum is σ = 27276672. Its totient is φ = 17047800.

The previous prime is 21878081. The next prime is 21878089. The reversal of 21878087 is 78087812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21878087 - 2⁴ = 21878071 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 (21878081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 141989 + ... + 142142.

It is an arithmetic number, because the mean of its divisors is an integer number (3409584).

Almost surely, 2^21878087 is an apocalyptic number.

21878087 is a deficient number, since it is larger than the sum of its proper divisors (5398585).

21878087 is a wasteful number, since it uses less digits than its factorization.

21878087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284149.

The product of its (nonzero) digits is 50176, while the sum is 41.

The square root of 21878087 is about 4677.4017360069. The cubic root of 21878087 is about 279.6853906835.

The spelling of 21878087 in words is "twenty-one million, eight hundred seventy-eight thousand, eighty-seven".