20400280 has 16 divisors (see below), whose sum is σ = 45900720. Its totient is φ = 8160096.

The previous prime is 20400277. The next prime is 20400301. The reversal of 20400280 is 8200402.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 254964 + ... + 255043.

It is an arithmetic number, because the mean of its divisors is an integer number (2868795).

Almost surely, 2^20400280 is an apocalyptic number.

20400280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20400280 is an abundant number, since it is smaller than the sum of its proper divisors (25500440).

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

20400280 is a wasteful number, since it uses less digits than its factorization.

20400280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510018 (or 510014 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 20400280 is about 4516.6669126691. Note that the first 3 decimals coincide. The cubic root of 20400280 is about 273.2406917188.

Adding to 20400280 its reverse (8200402), we get a palindrome (28600682).

The spelling of 20400280 in words is "twenty million, four hundred thousand, two hundred eighty".