331505981 has 2 divisors, whose sum is σ = 331505982. Its totient is φ = 331505980.

The previous prime is 331505959. The next prime is 331505987. The reversal of 331505981 is 189505133.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166152100 + 165353881 = 12890^2 + 12859^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-331505981 is a prime.

It is a super-2 number, since 2×331505981² = 219792430877544722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (331505987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165752990 + 165752991.

It is an arithmetic number, because the mean of its divisors is an integer number (165752991).

Almost surely, 2^331505981 is an apocalyptic number.

It is an amenable number.

331505981 is a deficient number, since it is larger than the sum of its proper divisors (1).

331505981 is an equidigital number, since it uses as much as digits as its factorization.

331505981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16200, while the sum is 35.

The square root of 331505981 is about 18207.3057040299. The cubic root of 331505981 is about 692.0919366474.

The spelling of 331505981 in words is "three hundred thirty-one million, five hundred five thousand, nine hundred eighty-one".