251121749 has 4 divisors (see below), whose sum is σ = 251264064. Its totient is φ = 250979436.

The previous prime is 251121743. The next prime is 251121809. The reversal of 251121749 is 947121152.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 251121749 - 2²⁴ = 234344533 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 (251121743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 68477 + ... + 72050.

It is an arithmetic number, because the mean of its divisors is an integer number (62816016).

Almost surely, 2^251121749 is an apocalyptic number.

It is an amenable number.

251121749 is a deficient number, since it is larger than the sum of its proper divisors (142315).

251121749 is a wasteful number, since it uses less digits than its factorization.

251121749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142314.

The product of its digits is 5040, while the sum is 32.

The square root of 251121749 is about 15846.8214162967. The cubic root of 251121749 is about 630.9013293374.

The spelling of 251121749 in words is "two hundred fifty-one million, one hundred twenty-one thousand, seven hundred forty-nine".