21874387 has 4 divisors (see below), whose sum is σ = 21885696. Its totient is φ = 21863080.

The previous prime is 21874367. The next prime is 21874397. The reversal of 21874387 is 78347812.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21874387 - 2¹⁵ = 21841619 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21874327) 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, 1939 + ... + 6892.

It is an arithmetic number, because the mean of its divisors is an integer number (5471424).

It is a vampire number, since it can be written as 2477 ⋅ 8831 (with its own digits).

Almost surely, 2^21874387 is an apocalyptic number.

21874387 is a deficient number, since it is larger than the sum of its proper divisors (11309).

21874387 is an equidigital number, since it uses as much as digits as its factorization.

21874387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11308.

The product of its digits is 75264, while the sum is 40.

The square root of 21874387 is about 4677.0062005518. The cubic root of 21874387 is about 279.6696230909.

The spelling of 21874387 in words is "twenty-one million, eight hundred seventy-four thousand, three hundred eighty-seven".