15643691 has 6 divisors (see below), whose sum is σ = 18197820. Its totient is φ = 13408836.

The previous prime is 15643679. The next prime is 15643699. The reversal of 15643691 is 19634651.

It is not a de Polignac number, because 15643691 - 2¹⁸ = 15381547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15643699) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 159581 + ... + 159678.

It is an arithmetic number, because the mean of its divisors is an integer number (3032970).

Almost surely, 2^15643691 is an apocalyptic number.

15643691 is a deficient number, since it is larger than the sum of its proper divisors (2554129).

15643691 is an equidigital number, since it uses as much as digits as its factorization.

15643691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319273 (or 319266 counting only the distinct ones).

The product of its digits is 19440, while the sum is 35.

The square root of 15643691 is about 3955.2106138612. The cubic root of 15643691 is about 250.0996456111.

The spelling of 15643691 in words is "fifteen million, six hundred forty-three thousand, six hundred ninety-one".