2564561820 has 24 divisors (see below), whose sum is σ = 7180773264. Its totient is φ = 683883136.

The previous prime is 2564561807. The next prime is 2564561821. The reversal of 2564561820 is 281654652.

2564561820 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2564561821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21371289 + ... + 21371408.

It is an arithmetic number, because the mean of its divisors is an integer number (299198886).

Almost surely, 2^2564561820 is an apocalyptic number.

2564561820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2564561820 is an abundant number, since it is smaller than the sum of its proper divisors (4616211444).

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

2564561820 is a wasteful number, since it uses less digits than its factorization.

2564561820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42742709 (or 42742707 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 39.

The square root of 2564561820 is about 50641.5029397825. The cubic root of 2564561820 is about 1368.7928379245.

The spelling of 2564561820 in words is "two billion, five hundred sixty-four million, five hundred sixty-one thousand, eight hundred twenty".