21842251 has 4 divisors (see below), whose sum is σ = 21911472. Its totient is φ = 21773032.

The previous prime is 21842243. The next prime is 21842269. The reversal of 21842251 is 15224812.

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 21842251 - 2³ = 21842243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21842221) 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, 34135 + ... + 34768.

It is an arithmetic number, because the mean of its divisors is an integer number (5477868).

Almost surely, 2^21842251 is an apocalyptic number.

21842251 is a deficient number, since it is larger than the sum of its proper divisors (69221).

21842251 is an equidigital number, since it uses as much as digits as its factorization.

21842251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69220.

The product of its digits is 1280, while the sum is 25.

The square root of 21842251 is about 4673.5694067811. The cubic root of 21842251 is about 279.5326003131.

The spelling of 21842251 in words is "twenty-one million, eight hundred forty-two thousand, two hundred fifty-one".