18861251 has 4 divisors (see below), whose sum is σ = 19034400. Its totient is φ = 18688104.

The previous prime is 18861247. The next prime is 18861277. The reversal of 18861251 is 15216881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15216881 = 661 ⋅23021.

It is a cyclic number.

It is not a de Polignac number, because 18861251 - 2² = 18861247 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18860251) 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, 86411 + ... + 86628.

It is an arithmetic number, because the mean of its divisors is an integer number (4758600).

Almost surely, 2^18861251 is an apocalyptic number.

18861251 is a deficient number, since it is larger than the sum of its proper divisors (173149).

18861251 is a wasteful number, since it uses less digits than its factorization.

18861251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173148.

The product of its digits is 3840, while the sum is 32.

The square root of 18861251 is about 4342.9541788971. The cubic root of 18861251 is about 266.1890368627.

The spelling of 18861251 in words is "eighteen million, eight hundred sixty-one thousand, two hundred fifty-one".