16399691 has 16 divisors (see below), whose sum is σ = 20537088. Its totient is φ = 12722400.

The previous prime is 16399681. The next prime is 16399729. The reversal of 16399691 is 19699361.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 16399691 - 2¹⁰ = 16398667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16399601) 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, 28436 + ... + 29006.

It is an arithmetic number, because the mean of its divisors is an integer number (1283568).

Almost surely, 2^16399691 is an apocalyptic number.

16399691 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

16399691 is a deficient number, since it is larger than the sum of its proper divisors (4137397).

16399691 is a wasteful number, since it uses less digits than its factorization.

16399691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 962.

The product of its digits is 78732, while the sum is 44.

The square root of 16399691 is about 4049.6531950279. The cubic root of 16399691 is about 254.0652228809.

The spelling of 16399691 in words is "sixteen million, three hundred ninety-nine thousand, six hundred ninety-one".