20840280 has 32 divisors (see below), whose sum is σ = 62521200. Its totient is φ = 5557376.

The previous prime is 20840269. The next prime is 20840293. The reversal of 20840280 is 8204802.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20840280.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86715 + ... + 86954.

Almost surely, 2^20840280 is an apocalyptic number.

20840280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20840280 is an abundant number, since it is smaller than the sum of its proper divisors (41680920).

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

20840280 is a wasteful number, since it uses less digits than its factorization.

20840280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173683 (or 173679 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 20840280 is about 4565.1155516591. The cubic root of 20840280 is about 275.1911838599.

The spelling of 20840280 in words is "twenty million, eight hundred forty thousand, two hundred eighty".