201990661 has 2 divisors, whose sum is σ = 201990662. Its totient is φ = 201990660.

The previous prime is 201990647. The next prime is 201990667. The reversal of 201990661 is 166099102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 194184225 + 7806436 = 13935^2 + 2794^2 .

It is a cyclic number.

It is not a de Polignac number, because 201990661 - 2⁵ = 201990629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201990667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100995330 + 100995331.

It is an arithmetic number, because the mean of its divisors is an integer number (100995331).

Almost surely, 2^201990661 is an apocalyptic number.

It is an amenable number.

201990661 is a deficient number, since it is larger than the sum of its proper divisors (1).

201990661 is an equidigital number, since it uses as much as digits as its factorization.

201990661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 201990661 is about 14212.3418548809. The cubic root of 201990661 is about 586.7373884196.

The spelling of 201990661 in words is "two hundred one million, nine hundred ninety thousand, six hundred sixty-one".