21483251 has 4 divisors (see below), whose sum is σ = 21785904. Its totient is φ = 21180600.

The previous prime is 21483239. The next prime is 21483263. The reversal of 21483251 is 15238412.

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 (21483239) and next prime (21483263).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21483251 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21483251.

It is not an unprimeable number, because it can be changed into a prime (21483211) 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, 151220 + ... + 151361.

It is an arithmetic number, because the mean of its divisors is an integer number (5446476).

Almost surely, 2^21483251 is an apocalyptic number.

21483251 is a deficient number, since it is larger than the sum of its proper divisors (302653).

21483251 is an equidigital number, since it uses as much as digits as its factorization.

21483251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302652.

The product of its digits is 1920, while the sum is 26.

The square root of 21483251 is about 4635.0028047456. The cubic root of 21483251 is about 277.9926632296.

Subtracting from 21483251 its sum of digits (26), we obtain a square (21483225 = 4635²).

The spelling of 21483251 in words is "twenty-one million, four hundred eighty-three thousand, two hundred fifty-one".