15771781640 has 32 divisors (see below), whose sum is σ = 35524791000. Its totient is φ = 6301906944.

The previous prime is 15771781621. The next prime is 15771781673. The reversal of 15771781640 is 4618717751.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6249534916 + 9522246724 = 79054^2 + 97582^2 .

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, 175055 + ... + 249374.

Almost surely, 2^15771781640 is an apocalyptic number.

15771781640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15771781640 is an abundant number, since it is smaller than the sum of its proper divisors (19753009360).

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

15771781640 is a wasteful number, since it uses less digits than its factorization.

15771781640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425369 (or 425365 counting only the distinct ones).

The product of its (nonzero) digits is 329280, while the sum is 47.

The spelling of 15771781640 in words is "fifteen billion, seven hundred seventy-one million, seven hundred eighty-one thousand, six hundred forty".