21917874 has 32 divisors (see below), whose sum is σ = 48939264. Its totient is φ = 6486480.

The previous prime is 21917867. The next prime is 21917891. The reversal of 21917874 is 47871912.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1024 + ... + 6699.

It is an arithmetic number, because the mean of its divisors is an integer number (1529352).

Almost surely, 2^21917874 is an apocalyptic number.

21917874 is an abundant number, since it is smaller than the sum of its proper divisors (27021390).

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

21917874 is a wasteful number, since it uses less digits than its factorization.

21917874 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7782.

The product of its digits is 28224, while the sum is 39.

The square root of 21917874 is about 4681.6529132348. The cubic root of 21917874 is about 279.8548312114.

It can be divided in two parts, 21917 and 874, that added together give a triangular number (22791 = T₂₁₃).

The spelling of 21917874 in words is "twenty-one million, nine hundred seventeen thousand, eight hundred seventy-four".