157961981 has 2 divisors, whose sum is σ = 157961982. Its totient is φ = 157961980.

The previous prime is 157961941. The next prime is 157961987. The reversal of 157961981 is 189169751.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 115906756 + 42055225 = 10766^2 + 6485^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-157961981 is a prime.

It is a super-2 number, since 2×157961981² = 49903974882888722, 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 (157961987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78980990 + 78980991.

It is an arithmetic number, because the mean of its divisors is an integer number (78980991).

Almost surely, 2^157961981 is an apocalyptic number.

It is an amenable number.

157961981 is a deficient number, since it is larger than the sum of its proper divisors (1).

157961981 is an equidigital number, since it uses as much as digits as its factorization.

157961981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 47.

The square root of 157961981 is about 12568.2926843705. The cubic root of 157961981 is about 540.5686522225.

The spelling of 157961981 in words is "one hundred fifty-seven million, nine hundred sixty-one thousand, nine hundred eighty-one".