15615561 has 16 divisors (see below), whose sum is σ = 22498560. Its totient is φ = 9576960.

The previous prime is 15615559. The next prime is 15615581. The reversal of 15615561 is 16551651.

15615561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 15615561 - 2¹ = 15615559 is a prime.

It is a super-3 number, since 3×15615561³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (15615581) 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, 16345 + ... + 17273.

It is an arithmetic number, because the mean of its divisors is an integer number (1406160).

Almost surely, 2^15615561 is an apocalyptic number.

It is an amenable number.

15615561 is a deficient number, since it is larger than the sum of its proper divisors (6882999).

15615561 is a wasteful number, since it uses less digits than its factorization.

15615561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1376.

The product of its digits is 4500, while the sum is 30.

The square root of 15615561 is about 3951.6529452876. The cubic root of 15615561 is about 249.9496485263.

The spelling of 15615561 in words is "fifteen million, six hundred fifteen thousand, five hundred sixty-one".