181402561 has 2 divisors, whose sum is σ = 181402562. Its totient is φ = 181402560.

The previous prime is 181402499. The next prime is 181402577. The reversal of 181402561 is 165204181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 176384961 + 5017600 = 13281^2 + 2240^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181402561 is a prime.

It is not a weakly prime, because it can be changed into another prime (181402961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90701280 + 90701281.

It is an arithmetic number, because the mean of its divisors is an integer number (90701281).

Almost surely, 2^181402561 is an apocalyptic number.

It is an amenable number.

181402561 is a deficient number, since it is larger than the sum of its proper divisors (1).

181402561 is an equidigital number, since it uses as much as digits as its factorization.

181402561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 181402561 is about 13468.5767993504. The cubic root of 181402561 is about 566.0843363031.

The spelling of 181402561 in words is "one hundred eighty-one million, four hundred two thousand, five hundred sixty-one".