21868151 has 4 divisors (see below), whose sum is σ = 21925632. Its totient is φ = 21810672.

The previous prime is 21868141. The next prime is 21868169. The reversal of 21868151 is 15186812.

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 21868151 - 2⁶ = 21868087 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 (21868111) 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, 28166 + ... + 28931.

It is an arithmetic number, because the mean of its divisors is an integer number (5481408).

Almost surely, 2^21868151 is an apocalyptic number.

21868151 is a deficient number, since it is larger than the sum of its proper divisors (57481).

21868151 is an equidigital number, since it uses as much as digits as its factorization.

21868151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57480.

The product of its digits is 3840, while the sum is 32.

The square root of 21868151 is about 4676.3394872485. The cubic root of 21868151 is about 279.6430442809.

The spelling of 21868151 in words is "twenty-one million, eight hundred sixty-eight thousand, one hundred fifty-one".