15781432640 has 56 divisors (see below), whose sum is σ = 38288625480. Its totient is φ = 6193461248.

The previous prime is 15781432621. The next prime is 15781432697. The reversal of 15781432640 is 4623418751.

It can be written as a sum of positive squares in 4 ways, for example, as 114404416 + 15667028224 = 10696^2 + 125168^2 .

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 448295 + ... + 482214.

It is an arithmetic number, because the mean of its divisors is an integer number (683725455).

Almost surely, 2^15781432640 is an apocalyptic number.

15781432640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15781432640 is an abundant number, since it is smaller than the sum of its proper divisors (22507192840).

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

15781432640 is an equidigital number, since it uses as much as digits as its factorization.

15781432640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 930579 (or 930569 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 41.

The spelling of 15781432640 in words is "fifteen billion, seven hundred eighty-one million, four hundred thirty-two thousand, six hundred forty".