661874197 has 4 divisors (see below), whose sum is σ = 690651360. Its totient is φ = 633097036.

The previous prime is 661874183. The next prime is 661874207. The reversal of 661874197 is 791478166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661874197 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 661874197.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661874117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14388547 + ... + 14388592.

It is an arithmetic number, because the mean of its divisors is an integer number (172662840).

Almost surely, 2^661874197 is an apocalyptic number.

It is an amenable number.

661874197 is a deficient number, since it is larger than the sum of its proper divisors (28777163).

661874197 is a wasteful number, since it uses less digits than its factorization.

661874197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28777162.

The product of its digits is 508032, while the sum is 49.

The square root of 661874197 is about 25726.9158081570. The cubic root of 661874197 is about 871.4821246199.

The spelling of 661874197 in words is "six hundred sixty-one million, eight hundred seventy-four thousand, one hundred ninety-seven".