249601981 has 2 divisors, whose sum is σ = 249601982. Its totient is φ = 249601980.

The previous prime is 249601951. The next prime is 249602009. The reversal of 249601981 is 189106942.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 176225625 + 73376356 = 13275^2 + 8566^2 .

It is a cyclic number.

It is not a de Polignac number, because 249601981 - 2⁷ = 249601853 is a prime.

It is a super-2 number, since 2×249601981² = 124602297838248722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (249601901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124800990 + 124800991.

It is an arithmetic number, because the mean of its divisors is an integer number (124800991).

Almost surely, 2^249601981 is an apocalyptic number.

It is an amenable number.

249601981 is a deficient number, since it is larger than the sum of its proper divisors (1).

249601981 is an equidigital number, since it uses as much as digits as its factorization.

249601981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 249601981 is about 15798.7968212772. The cubic root of 249601981 is about 629.6260323611.

The spelling of 249601981 in words is "two hundred forty-nine million, six hundred one thousand, nine hundred eighty-one".