251840081 has 4 divisors (see below), whose sum is σ = 257982564. Its totient is φ = 245697600.

The previous prime is 251840077. The next prime is 251840101. The reversal of 251840081 is 180048152.

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

It can be written as a sum of positive squares in 2 ways, for example, as 38241856 + 213598225 = 6184^2 + 14615^2 .

It is a cyclic number.

It is not a de Polignac number, because 251840081 - 2² = 251840077 is a prime.

It is a super-2 number, since 2×251840081² = 126846852796173122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (251840581) 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, 3071180 + ... + 3071261.

It is an arithmetic number, because the mean of its divisors is an integer number (64495641).

Almost surely, 2^251840081 is an apocalyptic number.

It is an amenable number.

251840081 is a deficient number, since it is larger than the sum of its proper divisors (6142483).

251840081 is an equidigital number, since it uses as much as digits as its factorization.

251840081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6142482.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 251840081 is about 15869.4700919722. The cubic root of 251840081 is about 631.5023195994.

The spelling of 251840081 in words is "two hundred fifty-one million, eight hundred forty thousand, eighty-one".