20731242 has 64 divisors (see below), whose sum is σ = 50641920. Its totient is φ = 5526144.

The previous prime is 20731241. The next prime is 20731247. The reversal of 20731242 is 24213702.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (20731241) 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, 66078 + ... + 66390.

It is an arithmetic number, because the mean of its divisors is an integer number (791280).

Almost surely, 2^20731242 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20731242, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25320960).

20731242 is an abundant number, since it is smaller than the sum of its proper divisors (29910678).

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

20731242 is a wasteful number, since it uses less digits than its factorization.

20731242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 427.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 20731242 is about 4553.1573660483. The cubic root of 20731242 is about 274.7104036796.

Adding to 20731242 its reverse (24213702), we get a palindrome (44944944).

The spelling of 20731242 in words is "twenty million, seven hundred thirty-one thousand, two hundred forty-two".