15821981265 has 8 divisors (see below), whose sum is σ = 25315170048. Its totient is φ = 8438390000.

The previous prime is 15821981261. The next prime is 15821981281. The reversal of 15821981265 is 56218912851.

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

It is not a de Polignac number, because 15821981265 - 2² = 15821981261 is a prime.

It is a super-2 number, since 2×15821981265² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (15821981261) 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, 527399361 + ... + 527399390.

It is an arithmetic number, because the mean of its divisors is an integer number (3164396256).

Almost surely, 2^15821981265 is an apocalyptic number.

15821981265 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

15821981265 is a deficient number, since it is larger than the sum of its proper divisors (9493188783).

15821981265 is a wasteful number, since it uses less digits than its factorization.

15821981265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1054798759.

The product of its digits is 345600, while the sum is 48.

The spelling of 15821981265 in words is "fifteen billion, eight hundred twenty-one million, nine hundred eighty-one thousand, two hundred sixty-five".