16401649591 has 4 divisors (see below), whose sum is σ = 16401958384. Its totient is φ = 16401340800.

The previous prime is 16401649529. The next prime is 16401649609. The reversal of 16401649591 is 19594610461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19594610461 = 61343 ⋅319427.

It is a cyclic number.

It is not a de Polignac number, because 16401649591 - 2¹¹ = 16401647543 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 (16401649501) 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, 52155 + ... + 188476.

It is an arithmetic number, because the mean of its divisors is an integer number (4100489596).

Almost surely, 2^16401649591 is an apocalyptic number.

16401649591 is a deficient number, since it is larger than the sum of its proper divisors (308793).

16401649591 is an equidigital number, since it uses as much as digits as its factorization.

16401649591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308792.

The product of its (nonzero) digits is 233280, while the sum is 46.

The spelling of 16401649591 in words is "sixteen billion, four hundred one million, six hundred forty-nine thousand, five hundred ninety-one".