15660221660 has 48 divisors (see below), whose sum is σ = 33182714880. Its totient is φ = 6207915840.

The previous prime is 15660221639. The next prime is 15660221663. The reversal of 15660221660 is 6612206651.

It is a self number, because there is not a number n which added to its sum of digits gives 15660221660.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15660221663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1000817 + ... + 1016343.

It is an arithmetic number, because the mean of its divisors is an integer number (691306560).

Almost surely, 2^15660221660 is an apocalyptic number.

15660221660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15660221660 is an abundant number, since it is smaller than the sum of its proper divisors (17522493220).

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

15660221660 is a wasteful number, since it uses less digits than its factorization.

15660221660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15986 (or 15984 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The spelling of 15660221660 in words is "fifteen billion, six hundred sixty million, two hundred twenty-one thousand, six hundred sixty".