251121233421 has 10 divisors (see below), whose sum is σ = 375131719182. Its totient is φ = 167414155560.

The previous prime is 251121233393. The next prime is 251121233497. The reversal of 251121233421 is 124332121152.

It is a happy number.

251121233421 is a `hidden beast` number, since 2 + 5 + 1 + 1 + 2 + 1 + 233 + 421 = 666.

It can be written as a sum of positive squares in only one way, i.e., 251076155625 + 45077796 = 501075^2 + 6714^2 .

It is not a de Polignac number, because 251121233421 - 2¹⁴ = 251121217037 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251121233021) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1550130990 + ... + 1550131151.

Almost surely, 2^251121233421 is an apocalyptic number.

It is an amenable number.

251121233421 is a deficient number, since it is larger than the sum of its proper divisors (124010485761).

251121233421 is an equidigital number, since it uses as much as digits as its factorization.

251121233421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3100262153 (or 3100262144 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

Adding to 251121233421 its reverse (124332121152), we get a palindrome (375453354573).

The spelling of 251121233421 in words is "two hundred fifty-one billion, one hundred twenty-one million, two hundred thirty-three thousand, four hundred twenty-one".