251606081 has 2 divisors, whose sum is σ = 251606082. Its totient is φ = 251606080.

The previous prime is 251606063. The next prime is 251606083. The reversal of 251606081 is 180606152.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219513856 + 32092225 = 14816^2 + 5665^2 .

It is a cyclic number.

It is not a de Polignac number, because 251606081 - 2²² = 247411777 is a prime.

It is a super-2 number, since 2×251606081² = 126611239992357122, which contains 22 as substring.

Together with 251606083, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (251606083) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125803040 + 125803041.

It is an arithmetic number, because the mean of its divisors is an integer number (125803041).

Almost surely, 2^251606081 is an apocalyptic number.

It is an amenable number.

251606081 is a deficient number, since it is larger than the sum of its proper divisors (1).

251606081 is an equidigital number, since it uses as much as digits as its factorization.

251606081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 251606081 is about 15862.0957316491. The cubic root of 251606081 is about 631.3066698658.

The spelling of 251606081 in words is "two hundred fifty-one million, six hundred six thousand, eighty-one".