21849251 has 4 divisors (see below), whose sum is σ = 21932592. Its totient is φ = 21765912.

The previous prime is 21849227. The next prime is 21849257. The reversal of 21849251 is 15294812.

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 21849251 - 2²² = 17654947 is a prime.

It is a super-2 number, since 2×21849251² = 954779538522002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21849257) 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, 41276 + ... + 41801.

It is an arithmetic number, because the mean of its divisors is an integer number (5483148).

Almost surely, 2^21849251 is an apocalyptic number.

21849251 is a deficient number, since it is larger than the sum of its proper divisors (83341).

21849251 is an equidigital number, since it uses as much as digits as its factorization.

21849251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83340.

The product of its digits is 5760, while the sum is 32.

The square root of 21849251 is about 4674.3182390590. The cubic root of 21849251 is about 279.5624586399.

The spelling of 21849251 in words is "twenty-one million, eight hundred forty-nine thousand, two hundred fifty-one".