156991693 has 2 divisors, whose sum is σ = 156991694. Its totient is φ = 156991692.

The previous prime is 156991649. The next prime is 156991711. The reversal of 156991693 is 396199651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 129345129 + 27646564 = 11373^2 + 5258^2 .

It is a cyclic number.

It is not a de Polignac number, because 156991693 - 2¹³ = 156983501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (156991633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78495846 + 78495847.

It is an arithmetic number, because the mean of its divisors is an integer number (78495847).

Almost surely, 2^156991693 is an apocalyptic number.

It is an amenable number.

156991693 is a deficient number, since it is larger than the sum of its proper divisors (1).

156991693 is an equidigital number, since it uses as much as digits as its factorization.

156991693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 393660, while the sum is 49.

The square root of 156991693 is about 12529.6325963693. The cubic root of 156991693 is about 539.4595564581.

It can be divided in two parts, 1569916 and 93, that added together give a square (1570009 = 1253²).

The spelling of 156991693 in words is "one hundred fifty-six million, nine hundred ninety-one thousand, six hundred ninety-three".