15811738640 has 20 divisors (see below), whose sum is σ = 36762292524. Its totient is φ = 6324695424.

The previous prime is 15811738639. The next prime is 15811738667. The reversal of 15811738640 is 4683711851.

It can be written as a sum of positive squares in 2 ways, for example, as 2980286464 + 12831452176 = 54592^2 + 113276^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×15811738640² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 15811738591 and 15811738600.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 98823287 + ... + 98823446.

Almost surely, 2^15811738640 is an apocalyptic number.

15811738640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15811738640 is an abundant number, since it is smaller than the sum of its proper divisors (20950553884).

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

15811738640 is a wasteful number, since it uses less digits than its factorization.

15811738640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 197646746 (or 197646740 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 44.

The spelling of 15811738640 in words is "fifteen billion, eight hundred eleven million, seven hundred thirty-eight thousand, six hundred forty".