13991565 has 16 divisors (see below), whose sum is σ = 25584768. Its totient is φ = 6396096.

The previous prime is 13991563. The next prime is 13991569. The reversal of 13991565 is 56519931.

It is not a de Polignac number, because 13991565 - 2¹ = 13991563 is a prime.

It is a super-2 number, since 2×13991565² = 391527782298450, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13991563) 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, 66522 + ... + 66731.

It is an arithmetic number, because the mean of its divisors is an integer number (1599048).

Almost surely, 2^13991565 is an apocalyptic number.

13991565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

13991565 is a deficient number, since it is larger than the sum of its proper divisors (11593203).

13991565 is a wasteful number, since it uses less digits than its factorization.

13991565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133268.

The product of its digits is 36450, while the sum is 39.

The square root of 13991565 is about 3740.5300426544. The cubic root of 13991565 is about 240.9658130027.

The spelling of 13991565 in words is "thirteen million, nine hundred ninety-one thousand, five hundred sixty-five".