251871842 has 4 divisors (see below), whose sum is σ = 377807766. Its totient is φ = 125935920.

The previous prime is 251871811. The next prime is 251871863. The reversal of 251871842 is 248178152.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 200477281 + 51394561 = 14159^2 + 7169^2 .

It is a super-3 number, since 3×251871842³ (a number of 26 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 251871796 and 251871805.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62967959 + ... + 62967962.

Almost surely, 2^251871842 is an apocalyptic number.

251871842 is a deficient number, since it is larger than the sum of its proper divisors (125935924).

251871842 is a wasteful number, since it uses less digits than its factorization.

251871842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125935923.

The product of its digits is 35840, while the sum is 38.

The square root of 251871842 is about 15870.4707554628. The cubic root of 251871842 is about 631.5288659458.

The spelling of 251871842 in words is "two hundred fifty-one million, eight hundred seventy-one thousand, eight hundred forty-two".