20787940 has 24 divisors (see below), whose sum is σ = 46223352. Its totient is φ = 7825920.

The previous prime is 20787917. The next prime is 20787941. The reversal of 20787940 is 4978702.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9884736 + 10903204 = 3144^2 + 3302^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20787940.

It is not an unprimeable number, because it can be changed into a prime (20787941) 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 7 ways as a sum of consecutive naturals, for example, 30231 + ... + 30910.

It is an arithmetic number, because the mean of its divisors is an integer number (1925973).

Almost surely, 2^20787940 is an apocalyptic number.

20787940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20787940 is an abundant number, since it is smaller than the sum of its proper divisors (25435412).

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

20787940 is a wasteful number, since it uses less digits than its factorization.

20787940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61167 (or 61165 counting only the distinct ones).

The product of its (nonzero) digits is 28224, while the sum is 37.

The square root of 20787940 is about 4559.3793437265. The cubic root of 20787940 is about 274.9606114385.

The spelling of 20787940 in words is "twenty million, seven hundred eighty-seven thousand, nine hundred forty".