661711599 has 24 divisors (see below), whose sum is σ = 993108480. Its totient is φ = 440294616.

The previous prime is 661711597. The next prime is 661711657. The reversal of 661711599 is 995117166.

It is not a de Polignac number, because 661711599 - 2¹ = 661711597 is a prime.

It is a super-2 number, since 2×661711599² = 875724480502273602, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661711597) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 140322 + ... + 144960.

It is an arithmetic number, because the mean of its divisors is an integer number (41379520).

Almost surely, 2^661711599 is an apocalyptic number.

661711599 is a deficient number, since it is larger than the sum of its proper divisors (331396881).

661711599 is an equidigital number, since it uses as much as digits as its factorization.

661711599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5241 (or 5229 counting only the distinct ones).

The product of its digits is 102060, while the sum is 45.

The square root of 661711599 is about 25723.7555384123. The cubic root of 661711599 is about 871.4107551380.

The spelling of 661711599 in words is "six hundred sixty-one million, seven hundred eleven thousand, five hundred ninety-nine".