20400440 has 32 divisors (see below), whose sum is σ = 46332000. Its totient is φ = 8083584.

The previous prime is 20400439. The next prime is 20400463. The reversal of 20400440 is 4400402.

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, 2021 + ... + 6699.

It is an arithmetic number, because the mean of its divisors is an integer number (1447875).

Almost surely, 2^20400440 is an apocalyptic number.

20400440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20400440 is an abundant number, since it is smaller than the sum of its proper divisors (25931560).

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

20400440 is a wasteful number, since it uses less digits than its factorization.

20400440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4799 (or 4795 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 14.

The square root of 20400440 is about 4516.6846248105. The cubic root of 20400440 is about 273.2414060619.

Adding to 20400440 its reverse (4400402), we get a palindrome (24800842).

The spelling of 20400440 in words is "twenty million, four hundred thousand, four hundred forty".