157768781 has 2 divisors, whose sum is σ = 157768782. Its totient is φ = 157768780.

The previous prime is 157768759. The next prime is 157768817. The reversal of 157768781 is 187867751.

It is a happy number.

Together with next prime (157768817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120253156 + 37515625 = 10966^2 + 6125^2 .

It is an emirp because it is prime and its reverse (187867751) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 157768781 - 2⁶ = 157768717 is a prime.

It is a super-2 number, since 2×157768781² = 49781976516451922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (157768081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78884390 + 78884391.

It is an arithmetic number, because the mean of its divisors is an integer number (78884391).

Almost surely, 2^157768781 is an apocalyptic number.

It is an amenable number.

157768781 is a deficient number, since it is larger than the sum of its proper divisors (1).

157768781 is an equidigital number, since it uses as much as digits as its factorization.

157768781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 658560, while the sum is 50.

The square root of 157768781 is about 12560.6043246334. The cubic root of 157768781 is about 540.3481762352.

The spelling of 157768781 in words is "one hundred fifty-seven million, seven hundred sixty-eight thousand, seven hundred eighty-one".