251223121 has 4 divisors (see below), whose sum is σ = 255481200. Its totient is φ = 246965044.

The previous prime is 251223097. The next prime is 251223169. The reversal of 251223121 is 121322152.

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 251223121 - 2¹¹ = 251221073 is a prime.

It is a super-2 number, since 2×251223121² = 126226113049961282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (251224121) 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, 2128951 + ... + 2129068.

It is an arithmetic number, because the mean of its divisors is an integer number (63870300).

Almost surely, 2^251223121 is an apocalyptic number.

It is an amenable number.

251223121 is a deficient number, since it is larger than the sum of its proper divisors (4258079).

251223121 is an equidigital number, since it uses as much as digits as its factorization.

251223121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4258078.

The product of its digits is 240, while the sum is 19.

The square root of 251223121 is about 15850.0195898933. The cubic root of 251223121 is about 630.9862113066.

Adding to 251223121 its reverse (121322152), we get a palindrome (372545273).

The spelling of 251223121 in words is "two hundred fifty-one million, two hundred twenty-three thousand, one hundred twenty-one".