20640946320 has 120 divisors (see below), whose sum is σ = 69955399800. Its totient is φ = 5453733888.

The previous prime is 20640946289. The next prime is 20640946331. The reversal of 20640946320 is 2364904602.

20640946320 is a `hidden beast` number, since 2 + 0 + 640 + 9 + 4 + 6 + 3 + 2 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 6957561744 + 13683384576 = 83412^2 + 116976^2 .

It is a tau number, because it is divible by the number of its divisors (120).

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53025 + ... + 209984.

It is an arithmetic number, because the mean of its divisors is an integer number (582961665).

Almost surely, 2^20640946320 is an apocalyptic number.

20640946320 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 20640946320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34977699900).

20640946320 is an abundant number, since it is smaller than the sum of its proper divisors (49314453480).

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

20640946320 is a wasteful number, since it uses less digits than its factorization.

20640946320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263137 (or 263128 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 36.

The spelling of 20640946320 in words is "twenty billion, six hundred forty million, nine hundred forty-six thousand, three hundred twenty".