661947123939 has 8 divisors (see below), whose sum is σ = 882645929232. Its totient is φ = 441273200640.

The previous prime is 661947123913. The next prime is 661947123941. The reversal of 661947123939 is 939321749166.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661947123939 - 2²⁰ = 661946075363 is a prime.

It is a super-2 number, since 2×661947123939² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661947123949) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6158334 + ... + 6264899.

It is an arithmetic number, because the mean of its divisors is an integer number (110330741154).

Almost surely, 2^661947123939 is an apocalyptic number.

661947123939 is a deficient number, since it is larger than the sum of its proper divisors (220698805293).

661947123939 is a wasteful number, since it uses less digits than its factorization.

661947123939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12440997.

The product of its digits is 13226976, while the sum is 60.

The spelling of 661947123939 in words is "six hundred sixty-one billion, nine hundred forty-seven million, one hundred twenty-three thousand, nine hundred thirty-nine".