20780649 has 12 divisors (see below), whose sum is σ = 30315012. Its totient is φ = 13716000.

The previous prime is 20780581. The next prime is 20780657. The reversal of 20780649 is 94608702.

20780649 is a `hidden beast` number, since 2 + 0 + 7 + 8 + 0 + 649 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19740249 + 1040400 = 4443^2 + 1020^2 .

It is not a de Polignac number, because 20780649 - 2⁸ = 20780393 is a prime.

It is a super-2 number, since 2×20780649² = 863670745722402, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20780659) 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 11 ways as a sum of consecutive naturals, for example, 10522 + ... + 12339.

It is an arithmetic number, because the mean of its divisors is an integer number (2526251).

Almost surely, 2^20780649 is an apocalyptic number.

It is an amenable number.

20780649 is a deficient number, since it is larger than the sum of its proper divisors (9534363).

20780649 is a wasteful number, since it uses less digits than its factorization.

20780649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22968 (or 22965 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 20780649 is about 4558.5797130247. The cubic root of 20780649 is about 274.9284618325.

The spelling of 20780649 in words is "twenty million, seven hundred eighty thousand, six hundred forty-nine".