661203965 has 4 divisors (see below), whose sum is σ = 793444764. Its totient is φ = 528963168.

The previous prime is 661203953. The next prime is 661204003. The reversal of 661203965 is 569302166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 114532804 + 546671161 = 10702^2 + 23381^2 .

It is a cyclic number.

It is not a de Polignac number, because 661203965 - 2²⁶ = 594095101 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66120392 + ... + 66120401.

It is an arithmetic number, because the mean of its divisors is an integer number (198361191).

Almost surely, 2^661203965 is an apocalyptic number.

It is an amenable number.

661203965 is a deficient number, since it is larger than the sum of its proper divisors (132240799).

661203965 is a wasteful number, since it uses less digits than its factorization.

661203965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132240798.

The product of its (nonzero) digits is 58320, while the sum is 38.

The square root of 661203965 is about 25713.8866179347. The cubic root of 661203965 is about 871.1878630226.

The spelling of 661203965 in words is "six hundred sixty-one million, two hundred three thousand, nine hundred sixty-five".