195015661 has 2 divisors, whose sum is σ = 195015662. Its totient is φ = 195015660.

The previous prime is 195015659. The next prime is 195015671. The reversal of 195015661 is 166510591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 126225225 + 68790436 = 11235^2 + 8294^2 .

It is a cyclic number.

It is not a de Polignac number, because 195015661 - 2¹ = 195015659 is a prime.

It is a super-2 number, since 2×195015661² = 76062216070533842, which contains 22 as substring.

Together with 195015659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (195015671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97507830 + 97507831.

It is an arithmetic number, because the mean of its divisors is an integer number (97507831).

Almost surely, 2^195015661 is an apocalyptic number.

195015661 is the 7465-th centered heptagonal number.

It is an amenable number.

195015661 is a deficient number, since it is larger than the sum of its proper divisors (1).

195015661 is an equidigital number, since it uses as much as digits as its factorization.

195015661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8100, while the sum is 34.

The square root of 195015661 is about 13964.8007862626. The cubic root of 195015661 is about 579.9045235230.

The spelling of 195015661 in words is "one hundred ninety-five million, fifteen thousand, six hundred sixty-one".