16400621663 has 4 divisors (see below), whose sum is σ = 16401008160. Its totient is φ = 16400235168.

The previous prime is 16400621651. The next prime is 16400621689. The reversal of 16400621663 is 36612600461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36612600461 = 50989 ⋅718049.

It is a cyclic number.

It is not a de Polignac number, because 16400621663 - 2²⁰ = 16399573087 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 (16400621603) 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, 120458 + ... + 217511.

It is an arithmetic number, because the mean of its divisors is an integer number (4100252040).

Almost surely, 2^16400621663 is an apocalyptic number.

16400621663 is a deficient number, since it is larger than the sum of its proper divisors (386497).

16400621663 is an equidigital number, since it uses as much as digits as its factorization.

16400621663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386496.

The product of its (nonzero) digits is 31104, while the sum is 35.

The spelling of 16400621663 in words is "sixteen billion, four hundred million, six hundred twenty-one thousand, six hundred sixty-three".