157978661 has 2 divisors, whose sum is σ = 157978662. Its totient is φ = 157978660.

The previous prime is 157978553. The next prime is 157978669. The reversal of 157978661 is 166879751.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83156161 + 74822500 = 9119^2 + 8650^2 .

It is a cyclic number.

It is not a de Polignac number, because 157978661 - 2¹⁰ = 157977637 is a prime.

It is a super-3 number, since 3×157978661³ (a number of 26 digits) contains 333 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 (157978669) by changing a digit.

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, 78989330 + 78989331.

It is an arithmetic number, because the mean of its divisors is an integer number (78989331).

Almost surely, 2^157978661 is an apocalyptic number.

It is an amenable number.

157978661 is a deficient number, since it is larger than the sum of its proper divisors (1).

157978661 is an equidigital number, since it uses as much as digits as its factorization.

157978661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 635040, while the sum is 50.

The square root of 157978661 is about 12568.9562414705. The cubic root of 157978661 is about 540.5876786737.

The spelling of 157978661 in words is "one hundred fifty-seven million, nine hundred seventy-eight thousand, six hundred sixty-one".