16403391 has 20 divisors (see below), whose sum is σ = 24620112. Its totient is φ = 10883808.

The previous prime is 16403389. The next prime is 16403417. The reversal of 16403391 is 19330461.

It is not a de Polignac number, because 16403391 - 2¹ = 16403389 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16403311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 25030 + ... + 25676.

Almost surely, 2^16403391 is an apocalyptic number.

16403391 is a deficient number, since it is larger than the sum of its proper divisors (8216721).

16403391 is an equidigital number, since it uses as much as digits as its factorization.

16403391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 972 (or 963 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 16403391 is about 4050.1099985062. The cubic root of 16403391 is about 254.0843283352.

The spelling of 16403391 in words is "sixteen million, four hundred three thousand, three hundred ninety-one".