20307440 has 40 divisors (see below), whose sum is σ = 47424048. Its totient is φ = 8087040.

The previous prime is 20307439. The next prime is 20307457. The reversal of 20307440 is 4470302.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

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, 24635 + ... + 25445.

Almost surely, 2^20307440 is an apocalyptic number.

20307440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20307440 is an abundant number, since it is smaller than the sum of its proper divisors (27116608).

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

20307440 is a wasteful number, since it uses less digits than its factorization.

20307440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1137 (or 1131 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 20.

The square root of 20307440 is about 4506.3777027675. The cubic root of 20307440 is about 272.8255626869.

Adding to 20307440 its reverse (4470302), we get a palindrome (24777742).

The spelling of 20307440 in words is "twenty million, three hundred seven thousand, four hundred forty".