660921601 has 2 divisors, whose sum is σ = 660921602. Its totient is φ = 660921600.

The previous prime is 660921587. The next prime is 660921617. The reversal of 660921601 is 106129066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 355511025 + 305410576 = 18855^2 + 17476^2 .

It is a cyclic number.

It is not a de Polignac number, because 660921601 - 2⁹ = 660921089 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (660921301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330460800 + 330460801.

It is an arithmetic number, because the mean of its divisors is an integer number (330460801).

Almost surely, 2^660921601 is an apocalyptic number.

It is an amenable number.

660921601 is a deficient number, since it is larger than the sum of its proper divisors (1).

660921601 is an equidigital number, since it uses as much as digits as its factorization.

660921601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 660921601 is about 25708.3955353110. The cubic root of 660921601 is about 871.0638331581.

The spelling of 660921601 in words is "six hundred sixty million, nine hundred twenty-one thousand, six hundred one".