20404280 has 32 divisors (see below), whose sum is σ = 49442400. Its totient is φ = 7533696.

The previous prime is 20404261. The next prime is 20404331. The reversal of 20404280 is 8240402.

20404280 = 465² + 466² + ... + 544².

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

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, 19100 + ... + 20139.

It is an arithmetic number, because the mean of its divisors is an integer number (1545075).

Almost surely, 2^20404280 is an apocalyptic number.

20404280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20404280 is an abundant number, since it is smaller than the sum of its proper divisors (29038120).

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

20404280 is a wasteful number, since it uses less digits than its factorization.

20404280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39263 (or 39259 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

The square root of 20404280 is about 4517.1096953694. The cubic root of 20404280 is about 273.2585491754.

Adding to 20404280 its reverse (8240402), we get a palindrome (28644682).

The spelling of 20404280 in words is "twenty million, four hundred four thousand, two hundred eighty".