20891640000 has 1680 divisors, whose sum is σ = 97695227520. Its totient is φ = 3870720000.

The previous prime is 20891639971. The next prime is 20891640031. The reversal of 20891640000 is 4619802.

It is a tau number, because it is divible by the number of its divisors (1680).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a self number, because there is not a number n which added to its sum of digits gives 20891640000.

It is an unprimeable number.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 1099559991 + ... + 1099560009.

Almost surely, 2^20891640000 is an apocalyptic number.

20891640000 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 20891640000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48847613760).

20891640000 is an abundant number, since it is smaller than the sum of its proper divisors (76803587520).

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

20891640000 is a wasteful number, since it uses less digits than its factorization.

20891640000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The spelling of 20891640000 in words is "twenty billion, eight hundred ninety-one million, six hundred forty thousand".