661090949 has 2 divisors, whose sum is σ = 661090950. Its totient is φ = 661090948.

The previous prime is 661090879. The next prime is 661090967. The reversal of 661090949 is 949090166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 648058849 + 13032100 = 25457^2 + 3610^2 .

It is a cyclic number.

It is not a de Polignac number, because 661090949 - 2²⁸ = 392655493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661090979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330545474 + 330545475.

It is an arithmetic number, because the mean of its divisors is an integer number (330545475).

Almost surely, 2^661090949 is an apocalyptic number.

It is an amenable number.

661090949 is a deficient number, since it is larger than the sum of its proper divisors (1).

661090949 is an equidigital number, since it uses as much as digits as its factorization.

661090949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 104976, while the sum is 44.

The square root of 661090949 is about 25711.6889565816. The cubic root of 661090949 is about 871.1382243922.

The spelling of 661090949 in words is "six hundred sixty-one million, ninety thousand, nine hundred forty-nine".