20779940 has 24 divisors (see below), whose sum is σ = 44818872. Its totient is φ = 8087040.

The previous prime is 20779937. The next prime is 20779973. The reversal of 20779940 is 4997702.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3407716 + 17372224 = 1846^2 + 4168^2 .

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 20779894 and 20779903.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13301 + ... + 14780.

It is an arithmetic number, because the mean of its divisors is an integer number (1867453).

Almost surely, 2^20779940 is an apocalyptic number.

20779940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20779940 is an abundant number, since it is smaller than the sum of its proper divisors (24038932).

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

20779940 is a wasteful number, since it uses less digits than its factorization.

20779940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28127 (or 28125 counting only the distinct ones).

The product of its (nonzero) digits is 31752, while the sum is 38.

The square root of 20779940 is about 4558.5019469119. The cubic root of 20779940 is about 274.9253351016.

The spelling of 20779940 in words is "twenty million, seven hundred seventy-nine thousand, nine hundred forty".