20649603864 has 128 divisors (see below), whose sum is σ = 55520640000. Its totient is φ = 6380901504.

The previous prime is 20649603853. The next prime is 20649603901. The reversal of 20649603864 is 46830694602.

It is a super-2 number, since 2×20649603864² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4047187 + ... + 4052285.

It is an arithmetic number, because the mean of its divisors is an integer number (433755000).

Almost surely, 2^20649603864 is an apocalyptic number.

20649603864 is a gapful number since it is divisible by the number (24) 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 20649603864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27760320000).

20649603864 is an abundant number, since it is smaller than the sum of its proper divisors (34871036136).

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

20649603864 is a wasteful number, since it uses less digits than its factorization.

20649603864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5317 (or 5313 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 48.

The spelling of 20649603864 in words is "twenty billion, six hundred forty-nine million, six hundred three thousand, eight hundred sixty-four".