21982251 has 4 divisors (see below), whose sum is σ = 29309672. Its totient is φ = 14654832.

The previous prime is 21982249. The next prime is 21982253. The reversal of 21982251 is 15228912.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21982249) and next prime (21982253).

It is not a de Polignac number, because 21982251 - 2¹ = 21982249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21982253) 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, 3663706 + ... + 3663711.

It is an arithmetic number, because the mean of its divisors is an integer number (7327418).

Almost surely, 2^21982251 is an apocalyptic number.

21982251 is a deficient number, since it is larger than the sum of its proper divisors (7327421).

21982251 is an equidigital number, since it uses as much as digits as its factorization.

21982251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7327420.

The product of its digits is 2880, while the sum is 30.

The square root of 21982251 is about 4688.5233282986. The cubic root of 21982251 is about 280.1285591616.

The spelling of 21982251 in words is "twenty-one million, nine hundred eighty-two thousand, two hundred fifty-one".