661209795 has 48 divisors (see below), whose sum is σ = 1185955680. Its totient is φ = 340526592.

The previous prime is 661209767. The next prime is 661209797. The reversal of 661209795 is 597902166.

It is a happy number.

It is a Cunningham number, because it is equal to 25714²-1.

It is not a de Polignac number, because 661209795 - 2⁵ = 661209763 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 661209795.

It is not an unprimeable number, because it can be changed into a prime (661209797) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 230007 + ... + 232863.

It is an arithmetic number, because the mean of its divisors is an integer number (24707410).

Almost surely, 2^661209795 is an apocalyptic number.

661209795 is a deficient number, since it is larger than the sum of its proper divisors (524745885).

661209795 is a wasteful number, since it uses less digits than its factorization.

661209795 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3044 (or 3041 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 45.

The square root of 661209795 is about 25713.9999805553. Note that the first 4 decimals coincide. The cubic root of 661209795 is about 871.1904235085.

The spelling of 661209795 in words is "six hundred sixty-one million, two hundred nine thousand, seven hundred ninety-five".