20931240 has 128 divisors (see below), whose sum is σ = 69621120. Its totient is φ = 4992000.

The previous prime is 20931223. The next prime is 20931241. The reversal of 20931240 is 4213902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20931241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 133242 + ... + 133398.

It is an arithmetic number, because the mean of its divisors is an integer number (543915).

Almost surely, 2^20931240 is an apocalyptic number.

20931240 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 20931240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34810560).

20931240 is an abundant number, since it is smaller than the sum of its proper divisors (48689880).

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

20931240 is a wasteful number, since it uses less digits than its factorization.

20931240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283 (or 279 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 20931240 is about 4575.0672126210. The cubic root of 20931240 is about 275.5909715242.

It can be divided in two parts, 2093 and 1240, that added together give a palindrome (3333).

The spelling of 20931240 in words is "twenty million, nine hundred thirty-one thousand, two hundred forty".