19952123865 has 16 divisors (see below), whose sum is σ = 33801245568. Its totient is φ = 10015183616.

The previous prime is 19952123861. The next prime is 19952123887. The reversal of 19952123865 is 56832125991.

It is a happy number.

It is not a de Polignac number, because 19952123865 - 2² = 19952123861 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is not an unprimeable number, because it can be changed into a prime (19952123861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39121557 + ... + 39122066.

It is an arithmetic number, because the mean of its divisors is an integer number (2112577848).

Almost surely, 2^19952123865 is an apocalyptic number.

19952123865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

19952123865 is a deficient number, since it is larger than the sum of its proper divisors (13849121703).

19952123865 is a wasteful number, since it uses less digits than its factorization.

19952123865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78243648.

The product of its digits is 1166400, while the sum is 51.

The spelling of 19952123865 in words is "nineteen billion, nine hundred fifty-two million, one hundred twenty-three thousand, eight hundred sixty-five".