16399645668 has 144 divisors (see below), whose sum is σ = 50211799680. Its totient is φ = 4534263360.

The previous prime is 16399645651. The next prime is 16399645721. The reversal of 16399645668 is 86654699361.

16399645668 is a `hidden beast` number, since 1 + 6 + 3 + 9 + 9 + 64 + 566 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 715230 + ... + 737802.

Almost surely, 2^16399645668 is an apocalyptic number.

16399645668 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16399645668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25105899840).

16399645668 is an abundant number, since it is smaller than the sum of its proper divisors (33812154012).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16399645668 is a wasteful number, since it uses less digits than its factorization.

16399645668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22655 (or 22616 counting only the distinct ones).

The product of its digits is 50388480, while the sum is 63.

The spelling of 16399645668 in words is "sixteen billion, three hundred ninety-nine million, six hundred forty-five thousand, six hundred sixty-eight".