20217980 has 12 divisors (see below), whose sum is σ = 42457800. Its totient is φ = 8087184.

The previous prime is 20217949. The next prime is 20218013. The reversal of 20217980 is 8971202.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 505430 + ... + 505469.

It is an arithmetic number, because the mean of its divisors is an integer number (3538150).

Almost surely, 2^20217980 is an apocalyptic number.

20217980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20217980 is an abundant number, since it is smaller than the sum of its proper divisors (22239820).

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

20217980 is a wasteful number, since it uses less digits than its factorization.

20217980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1010908 (or 1010906 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 20217980 is about 4496.4408146889. The cubic root of 20217980 is about 272.4243484409.

It can be divided in two parts, 2021 and 7980, that added together give a palindrome (10001).

The spelling of 20217980 in words is "twenty million, two hundred seventeen thousand, nine hundred eighty".