75691981 has 2 divisors, whose sum is σ = 75691982. Its totient is φ = 75691980.

The previous prime is 75691961. The next prime is 75691999. The reversal of 75691981 is 18919657.

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., 42445225 + 33246756 = 6515^2 + 5766^2 .

It is a cyclic number.

It is not a de Polignac number, because 75691981 - 2⁷ = 75691853 is a prime.

It is a super-2 number, since 2×75691981² = 11458551975408722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (75691951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37845990 + 37845991.

It is an arithmetic number, because the mean of its divisors is an integer number (37845991).

Almost surely, 2^75691981 is an apocalyptic number.

It is an amenable number.

75691981 is a deficient number, since it is larger than the sum of its proper divisors (1).

75691981 is an equidigital number, since it uses as much as digits as its factorization.

75691981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 46.

The square root of 75691981 is about 8700.1138498298. The cubic root of 75691981 is about 423.0093405565.

The spelling of 75691981 in words is "seventy-five million, six hundred ninety-one thousand, nine hundred eighty-one".