20864780 has 48 divisors (see below), whose sum is σ = 46902240. Its totient is φ = 7769088.

The previous prime is 20864773. The next prime is 20864783. The reversal of 20864780 is 8746802.

It is a self number, because there is not a number n which added to its sum of digits gives 20864780.

It is not an unprimeable number, because it can be changed into a prime (20864783) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36779 + ... + 37341.

It is an arithmetic number, because the mean of its divisors is an integer number (977130).

Almost surely, 2^20864780 is an apocalyptic number.

20864780 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 20864780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23451120).

20864780 is an abundant number, since it is smaller than the sum of its proper divisors (26037460).

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

20864780 is a wasteful number, since it uses less digits than its factorization.

20864780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 698 (or 696 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 20864780 is about 4567.7981566615. The cubic root of 20864780 is about 275.2989806149.

The spelling of 20864780 in words is "twenty million, eight hundred sixty-four thousand, seven hundred eighty".