20943840 has 48 divisors (see below), whose sum is σ = 65974608. Its totient is φ = 5584896.

The previous prime is 20943827. The next prime is 20943841. The reversal of 20943840 is 4834902.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20943798 and 20943807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20943841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21337 + ... + 22296.

It is an arithmetic number, because the mean of its divisors is an integer number (1374471).

Almost surely, 2^20943840 is an apocalyptic number.

20943840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20943840 is an abundant number, since it is smaller than the sum of its proper divisors (45030768).

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

20943840 is a wasteful number, since it uses less digits than its factorization.

20943840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43651 (or 43643 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 20943840 is about 4576.4440344005. Note that the first 3 decimals coincide. The cubic root of 20943840 is about 275.6462596916.

The spelling of 20943840 in words is "twenty million, nine hundred forty-three thousand, eight hundred forty".