20861040 has 80 divisors (see below), whose sum is σ = 68486688. Its totient is φ = 5234688.

The previous prime is 20861033. The next prime is 20861051. The reversal of 20861040 is 4016802.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 20860998 and 20861016.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1524 + ... + 6636.

Almost surely, 2^20861040 is an apocalyptic number.

20861040 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 20861040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34243344).

20861040 is an abundant number, since it is smaller than the sum of its proper divisors (47625648).

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

20861040 is a wasteful number, since it uses less digits than its factorization.

20861040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5146 (or 5140 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 20861040 is about 4567.3887506977. The cubic root of 20861040 is about 275.2825305699.

Adding to 20861040 its reverse (4016802), we get a palindrome (24877842).

The spelling of 20861040 in words is "twenty million, eight hundred sixty-one thousand, forty".