15699661 has 4 divisors (see below), whose sum is σ = 15747424. Its totient is φ = 15651900.

The previous prime is 15699659. The next prime is 15699667. The reversal of 15699661 is 16699651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16699651 = 19 ⋅878929.

It is a cyclic number.

It is not a de Polignac number, because 15699661 - 2¹ = 15699659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15699667) 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, 23385 + ... + 24046.

It is an arithmetic number, because the mean of its divisors is an integer number (3936856).

Almost surely, 2^15699661 is an apocalyptic number.

It is an amenable number.

15699661 is a deficient number, since it is larger than the sum of its proper divisors (47763).

15699661 is an equidigital number, since it uses as much as digits as its factorization.

15699661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47762.

The product of its digits is 87480, while the sum is 43.

The square root of 15699661 is about 3962.2797730599. The cubic root of 15699661 is about 250.3975594508.

The spelling of 15699661 in words is "fifteen million, six hundred ninety-nine thousand, six hundred sixty-one".