20400240 has 80 divisors (see below), whose sum is σ = 72281088. Its totient is φ = 4662528.

The previous prime is 20400239. The next prime is 20400257. The reversal of 20400240 is 4200402.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

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 15 ways as a sum of consecutive naturals, for example, 4392 + ... + 7751.

Almost surely, 2^20400240 is an apocalyptic number.

20400240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20400240 is an abundant number, since it is smaller than the sum of its proper divisors (51880848).

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

20400240 is a wasteful number, since it uses less digits than its factorization.

20400240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12166 (or 12160 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 12.

The square root of 20400240 is about 4516.6624846229. The cubic root of 20400240 is about 273.2405131325.

Adding to 20400240 its reverse (4200402), we get a palindrome (24600642).

The spelling of 20400240 in words is "twenty million, four hundred thousand, two hundred forty".