16564321620 has 864 divisors, whose sum is σ = 68890663296. Its totient is φ = 3200440320.

The previous prime is 16564321561. The next prime is 16564321633. The reversal of 16564321620 is 2612346561.

16564321620 is a `hidden beast` number, since 1 + 6 + 5 + 6 + 4 + 3 + 21 + 620 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 199570099 + ... + 199570181.

It is an arithmetic number, because the mean of its divisors is an integer number (79734564).

Almost surely, 2^16564321620 is an apocalyptic number.

16564321620 is a gapful number since it is divisible by the number (10) 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 16564321620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34445331648).

16564321620 is an abundant number, since it is smaller than the sum of its proper divisors (52326341676).

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

16564321620 is a wasteful number, since it uses less digits than its factorization.

16564321620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162 (or 128 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 16564321620 in words is "sixteen billion, five hundred sixty-four million, three hundred twenty-one thousand, six hundred twenty".