20865845840 has 40 divisors (see below), whose sum is σ = 55443534720. Its totient is φ = 7154004096.

The previous prime is 20865845837. The next prime is 20865845843. The reversal of 20865845840 is 4854856802.

It is an interprime number because it is at equal distance from previous prime (20865845837) and next prime (20865845843).

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20865845843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18629660 + ... + 18630779.

It is an arithmetic number, because the mean of its divisors is an integer number (1386088368).

Almost surely, 2^20865845840 is an apocalyptic number.

20865845840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20865845840 is an abundant number, since it is smaller than the sum of its proper divisors (34577688880).

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

20865845840 is a wasteful number, since it uses less digits than its factorization.

20865845840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37260459 (or 37260453 counting only the distinct ones).

The product of its (nonzero) digits is 2457600, while the sum is 50.

The spelling of 20865845840 in words is "twenty billion, eight hundred sixty-five million, eight hundred forty-five thousand, eight hundred forty".