15661501556 has 12 divisors (see below), whose sum is σ = 27408669792. Its totient is φ = 7830453048.

The previous prime is 15661501553. The next prime is 15661501579. The reversal of 15661501556 is 65510516651.

It is a super-2 number, since 2×15661501556² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15661501553) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79121 + ... + 193863.

It is an arithmetic number, because the mean of its divisors is an integer number (2284055816).

Almost surely, 2^15661501556 is an apocalyptic number.

It is an amenable number.

15661501556 is a deficient number, since it is larger than the sum of its proper divisors (11747168236).

15661501556 is a wasteful number, since it uses less digits than its factorization.

15661501556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148870 (or 148868 counting only the distinct ones).

The product of its (nonzero) digits is 135000, while the sum is 41.

The spelling of 15661501556 in words is "fifteen billion, six hundred sixty-one million, five hundred one thousand, five hundred fifty-six".