631947661 has 2 divisors, whose sum is σ = 631947662. Its totient is φ = 631947660.

The previous prime is 631947649. The next prime is 631947677. The reversal of 631947661 is 166749136.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 561974436 + 69973225 = 23706^2 + 8365^2 .

It is a cyclic number.

It is not a de Polignac number, because 631947661 - 2¹⁵ = 631914893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (631947601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315973830 + 315973831.

It is an arithmetic number, because the mean of its divisors is an integer number (315973831).

Almost surely, 2^631947661 is an apocalyptic number.

It is an amenable number.

631947661 is a deficient number, since it is larger than the sum of its proper divisors (1).

631947661 is an equidigital number, since it uses as much as digits as its factorization.

631947661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 43.

The square root of 631947661 is about 25138.5691915829. The cubic root of 631947661 is about 858.1443950575.

The spelling of 631947661 in words is "six hundred thirty-one million, nine hundred forty-seven thousand, six hundred sixty-one".