20128251 has 16 divisors (see below), whose sum is σ = 31530240. Its totient is φ = 11260320.

The previous prime is 20128223. The next prime is 20128279. The reversal of 20128251 is 15282102.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20128223) and next prime (20128279).

It is not a de Polignac number, because 20128251 - 2⁵ = 20128219 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20128211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23031 + ... + 23888.

It is an arithmetic number, because the mean of its divisors is an integer number (1970640).

Almost surely, 2^20128251 is an apocalyptic number.

20128251 is a deficient number, since it is larger than the sum of its proper divisors (11401989).

20128251 is a wasteful number, since it uses less digits than its factorization.

20128251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46946.

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 20128251 is about 4486.4519388934. The cubic root of 20128251 is about 272.0207371373.

It can be divided in two parts, 20 and 128251, that added together give a triangular number (128271 = T₅₀₆).

The spelling of 20128251 in words is "twenty million, one hundred twenty-eight thousand, two hundred fifty-one".