15661040 has 40 divisors (see below), whose sum is σ = 36665808. Its totient is φ = 6220800.

The previous prime is 15661033. The next prime is 15661069. The reversal of 15661040 is 4016651.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 15660997 and 15661015.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12440 + ... + 13640.

Almost surely, 2^15661040 is an apocalyptic number.

15661040 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 15661040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18332904).

15661040 is an abundant number, since it is smaller than the sum of its proper divisors (21004768).

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

15661040 is a wasteful number, since it uses less digits than its factorization.

15661040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1377 (or 1371 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 15661040 is about 3957.4031889612. The cubic root of 15661040 is about 250.1920657386.

Adding to 15661040 its reverse (4016651), we get a palindrome (19677691).

The spelling of 15661040 in words is "fifteen million, six hundred sixty-one thousand, forty".