15645969856 has 126 divisors (see below), whose sum is σ = 36257274704. Its totient is φ = 6692505600.

The previous prime is 15645969827. The next prime is 15645969869. The reversal of 15645969856 is 65896954651.

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2234521 + ... + 2241511.

Almost surely, 2^15645969856 is an apocalyptic number.

15645969856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15645969856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18128637352).

15645969856 is an abundant number, since it is smaller than the sum of its proper divisors (20611304848).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

15645969856 is a wasteful number, since it uses less digits than its factorization.

15645969856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7059 (or 7021 counting only the distinct ones).

The product of its digits is 69984000, while the sum is 64.

The spelling of 15645969856 in words is "fifteen billion, six hundred forty-five million, nine hundred sixty-nine thousand, eight hundred fifty-six".