15667661 has 4 divisors (see below), whose sum is σ = 15856512. Its totient is φ = 15478812.

The previous prime is 15667643. The next prime is 15667681. The reversal of 15667661 is 16676651.

15667661 is nontrivially palindromic in base 12.

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.

It is a cyclic number.

It is not a de Polignac number, because 15667661 - 2¹⁴ = 15651277 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 (15667601) 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, 94301 + ... + 94466.

It is an arithmetic number, because the mean of its divisors is an integer number (3964128).

Almost surely, 2^15667661 is an apocalyptic number.

It is an amenable number.

15667661 is a deficient number, since it is larger than the sum of its proper divisors (188851).

15667661 is an equidigital number, since it uses as much as digits as its factorization.

15667661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188850.

The product of its digits is 45360, while the sum is 38.

The square root of 15667661 is about 3958.2396339787. The cubic root of 15667661 is about 250.2273185757.

The spelling of 15667661 in words is "fifteen million, six hundred sixty-seven thousand, six hundred sixty-one".