20646321840 has 180 divisors, whose sum is σ = 73656555024. Its totient is φ = 5181769728.

The previous prime is 20646321809. The next prime is 20646321847. The reversal of 20646321840 is 4812364602.

20646321840 is a `hidden beast` number, since 2 + 0 + 6 + 4 + 632 + 18 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (180).

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

It is a junction number, because it is equal to n+sod(n) for n = 20646321795 and 20646321804.

It is not an unprimeable number, because it can be changed into a prime (20646321847) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 158469 + ... + 257691.

Almost surely, 2^20646321840 is an apocalyptic number.

20646321840 is a gapful number since it is divisible by the number (20) 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 20646321840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36828277512).

20646321840 is an abundant number, since it is smaller than the sum of its proper divisors (53010233184).

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

20646321840 is a wasteful number, since it uses less digits than its factorization.

20646321840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99276 (or 99250 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The spelling of 20646321840 in words is "twenty billion, six hundred forty-six million, three hundred twenty-one thousand, eight hundred forty".