20643880 has 64 divisors (see below), whose sum is σ = 51062400. Its totient is φ = 7476480.

The previous prime is 20643851. The next prime is 20643893. The reversal of 20643880 is 8834602.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16890 + ... + 18070.

It is an arithmetic number, because the mean of its divisors is an integer number (797850).

Almost surely, 2^20643880 is an apocalyptic number.

20643880 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 20643880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25531200).

20643880 is an abundant number, since it is smaller than the sum of its proper divisors (30418520).

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

20643880 is a wasteful number, since it uses less digits than its factorization.

20643880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1234 (or 1230 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 20643880 is about 4543.5536752634. The cubic root of 20643880 is about 274.3239814127.

The spelling of 20643880 in words is "twenty million, six hundred forty-three thousand, eight hundred eighty".