20781242 has 8 divisors (see below), whose sum is σ = 33005556. Its totient is φ = 9779392.

The previous prime is 20781239. The next prime is 20781251. The reversal of 20781242 is 24218702.

It can be written as a sum of positive squares in 2 ways, for example, as 16982641 + 3798601 = 4121^2 + 1949^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 305573 + ... + 305640.

Almost surely, 2^20781242 is an apocalyptic number.

20781242 is a deficient number, since it is larger than the sum of its proper divisors (12224314).

20781242 is a wasteful number, since it uses less digits than its factorization.

20781242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 611232.

The product of its (nonzero) digits is 1792, while the sum is 26.

The square root of 20781242 is about 4558.6447547489. The cubic root of 20781242 is about 274.9310769422.

Adding to 20781242 its reverse (24218702), we get a palindrome (44999944).

The spelling of 20781242 in words is "twenty million, seven hundred eighty-one thousand, two hundred forty-two".