20847940 has 48 divisors (see below), whose sum is σ = 46710720. Its totient is φ = 7793280.

The previous prime is 20847923. The next prime is 20847941. The reversal of 20847940 is 4974802.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 20847896 and 20847905.

It is not an unprimeable number, because it can be changed into a prime (20847941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31210 + ... + 31870.

It is an arithmetic number, because the mean of its divisors is an integer number (973140).

Almost surely, 2^20847940 is an apocalyptic number.

20847940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20847940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23355360).

20847940 is an abundant number, since it is smaller than the sum of its proper divisors (25862780).

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

20847940 is a wasteful number, since it uses less digits than its factorization.

20847940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 772 (or 770 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 20847940 is about 4565.9544456773. The cubic root of 20847940 is about 275.2248959190.

The spelling of 20847940 in words is "twenty million, eight hundred forty-seven thousand, nine hundred forty".