20657121810 has 96 divisors (see below), whose sum is σ = 54826917120. Its totient is φ = 4976584704.

The previous prime is 20657121757. The next prime is 20657121827. The reversal of 20657121810 is 1812175602.

20657121810 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×20657121810² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 194946 + ... + 281634.

It is an arithmetic number, because the mean of its divisors is an integer number (571113720).

Almost surely, 2^20657121810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20657121810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27413458560).

20657121810 is an abundant number, since it is smaller than the sum of its proper divisors (34169795310).

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

20657121810 is a wasteful number, since it uses less digits than its factorization.

20657121810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86772 (or 86759 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 33.

It can be divided in two parts, 206 and 57121810, that added together give a triangular number (57122016 = T₁₀₆₈₈).

The spelling of 20657121810 in words is "twenty billion, six hundred fifty-seven million, one hundred twenty-one thousand, eight hundred ten".