20840172 has 12 divisors (see below), whose sum is σ = 48627096. Its totient is φ = 6946720.

The previous prime is 20840167. The next prime is 20840173. The reversal of 20840172 is 27104802.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (20840173) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 868329 + ... + 868352.

It is an arithmetic number, because the mean of its divisors is an integer number (4052258).

Almost surely, 2^20840172 is an apocalyptic number.

It is an amenable number.

20840172 is an abundant number, since it is smaller than the sum of its proper divisors (27786924).

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

20840172 is a wasteful number, since it uses less digits than its factorization.

20840172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1736688 (or 1736686 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 20840172 is about 4565.1037228085. The cubic root of 20840172 is about 275.1907084872.

Adding to 20840172 its reverse (27104802), we get a palindrome (47944974).

It can be divided in two parts, 20840 and 172, that added together give a palindrome (21012).

The spelling of 20840172 in words is "twenty million, eight hundred forty thousand, one hundred seventy-two".