21877867 has 4 divisors (see below), whose sum is σ = 23866776. Its totient is φ = 19888960.

The previous prime is 21877859. The next prime is 21877879. The reversal of 21877867 is 76877812.

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 21877867 - 2³ = 21877859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21877837) 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, 994438 + ... + 994459.

It is an arithmetic number, because the mean of its divisors is an integer number (5966694).

Almost surely, 2^21877867 is an apocalyptic number.

21877867 is a deficient number, since it is larger than the sum of its proper divisors (1988909).

21877867 is a wasteful number, since it uses less digits than its factorization.

21877867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1988908.

The product of its digits is 263424, while the sum is 46.

The square root of 21877867 is about 4677.3782186178. The cubic root of 21877867 is about 279.6844532007.

Subtracting 21877867 from its reverse (76877812), we obtain a palindrome (54999945).

The spelling of 21877867 in words is "twenty-one million, eight hundred seventy-seven thousand, eight hundred sixty-seven".