15621256340 has 12 divisors (see below), whose sum is σ = 32804638356. Its totient is φ = 6248502528.

The previous prime is 15621256337. The next prime is 15621256367. The reversal of 15621256340 is 4365212651.

It can be written as a sum of positive squares in 2 ways, for example, as 10222827664 + 5398428676 = 101108^2 + 73474^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 15621256340.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 390531389 + ... + 390531428.

It is an arithmetic number, because the mean of its divisors is an integer number (2733719863).

Almost surely, 2^15621256340 is an apocalyptic number.

15621256340 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15621256340 is an abundant number, since it is smaller than the sum of its proper divisors (17183382016).

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

15621256340 is a wasteful number, since it uses less digits than its factorization.

15621256340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 781062826 (or 781062824 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 35.

Adding to 15621256340 its reverse (4365212651), we get a palindrome (19986468991).

The spelling of 15621256340 in words is "fifteen billion, six hundred twenty-one million, two hundred fifty-six thousand, three hundred forty".