20720042 has 24 divisors (see below), whose sum is σ = 38284164. Its totient is φ = 8356992.

The previous prime is 20720039. The next prime is 20720057. The reversal of 20720042 is 24002702.

It can be written as a sum of positive squares in 2 ways, for example, as 20259001 + 461041 = 4501^2 + 679^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a self number, because there is not a number n which added to its sum of digits gives 20720042.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4553 + ... + 7884.

Almost surely, 2^20720042 is an apocalyptic number.

20720042 is a deficient number, since it is larger than the sum of its proper divisors (17564122).

20720042 is a wasteful number, since it uses less digits than its factorization.

20720042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12470 (or 12463 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 17.

The square root of 20720042 is about 4551.9272841292. The cubic root of 20720042 is about 274.6609242392.

Adding to 20720042 its reverse (24002702), we get a palindrome (44722744).

The spelling of 20720042 in words is "twenty million, seven hundred twenty thousand, forty-two".