75151981 has 2 divisors, whose sum is σ = 75151982. Its totient is φ = 75151980.

The previous prime is 75151931. The next prime is 75152023. The reversal of 75151981 is 18915157.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59675625 + 15476356 = 7725^2 + 3934^2 .

It is an emirp because it is prime and its reverse (18915157) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-75151981 is a prime.

It is a super-3 number, since 3×75151981³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 75151981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (75151931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37575990 + 37575991.

It is an arithmetic number, because the mean of its divisors is an integer number (37575991).

Almost surely, 2^75151981 is an apocalyptic number.

It is an amenable number.

75151981 is a deficient number, since it is larger than the sum of its proper divisors (1).

75151981 is an equidigital number, since it uses as much as digits as its factorization.

75151981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12600, while the sum is 37.

The square root of 75151981 is about 8669.0242242135. The cubic root of 75151981 is about 422.0009976542. Note that the first 3 decimals are identical.

The spelling of 75151981 in words is "seventy-five million, one hundred fifty-one thousand, nine hundred eighty-one".