252181981 has 2 divisors, whose sum is σ = 252181982. Its totient is φ = 252181980.

The previous prime is 252181921. The next prime is 252181997. The reversal of 252181981 is 189181252.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 238239225 + 13942756 = 15435^2 + 3734^2 .

It is a cyclic number.

It is not a de Polignac number, because 252181981 - 2¹¹ = 252179933 is a prime.

It is a super-2 number, since 2×252181981² = 127191503082168722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 252181981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (252181901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 126090990 + 126090991.

It is an arithmetic number, because the mean of its divisors is an integer number (126090991).

Almost surely, 2^252181981 is an apocalyptic number.

It is an amenable number.

252181981 is a deficient number, since it is larger than the sum of its proper divisors (1).

252181981 is an equidigital number, since it uses as much as digits as its factorization.

252181981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11520, while the sum is 37.

The square root of 252181981 is about 15880.2386946796. The cubic root of 252181981 is about 631.7879678152.

The spelling of 252181981 in words is "two hundred fifty-two million, one hundred eighty-one thousand, nine hundred eighty-one".