194815661 has 2 divisors, whose sum is σ = 194815662. Its totient is φ = 194815660.

The previous prime is 194815657. The next prime is 194815697. The reversal of 194815661 is 166518491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 186868900 + 7946761 = 13670^2 + 2819^2 .

It is a cyclic number.

It is not a de Polignac number, because 194815661 - 2² = 194815657 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (194815961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97407830 + 97407831.

It is an arithmetic number, because the mean of its divisors is an integer number (97407831).

Almost surely, 2^194815661 is an apocalyptic number.

It is an amenable number.

194815661 is a deficient number, since it is larger than the sum of its proper divisors (1).

194815661 is an equidigital number, since it uses as much as digits as its factorization.

194815661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 41.

The square root of 194815661 is about 13957.6380881580. The cubic root of 194815661 is about 579.7062136794.

The spelling of 194815661 in words is "one hundred ninety-four million, eight hundred fifteen thousand, six hundred sixty-one".