16615406440 has 72 divisors (see below), whose sum is σ = 37975264290. Its totient is φ = 6542790144.

The previous prime is 16615406419. The next prime is 16615406491. The reversal of 16615406440 is 4460451661.

It can be written as a sum of positive squares in 9 ways, for example, as 3963206116 + 12652200324 = 62954^2 + 112482^2 .

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 16615406440.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 72556246 + ... + 72556474.

Almost surely, 2^16615406440 is an apocalyptic number.

16615406440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16615406440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18987632145).

16615406440 is an abundant number, since it is smaller than the sum of its proper divisors (21359857850).

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

16615406440 is an frugal number, since it uses more digits than its factorization.

16615406440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 647 (or 325 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 37.

The spelling of 16615406440 in words is "sixteen billion, six hundred fifteen million, four hundred six thousand, four hundred forty".