21820080 has 40 divisors (see below), whose sum is σ = 67642992. Its totient is φ = 5818624.

The previous prime is 21820069. The next prime is 21820087. The reversal of 21820080 is 8002812.

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

It is a super-2 number, since 2×21820080² = 952231782412800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21820087) 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, 45219 + ... + 45698.

Almost surely, 2^21820080 is an apocalyptic number.

21820080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21820080 is an abundant number, since it is smaller than the sum of its proper divisors (45822912).

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

21820080 is a wasteful number, since it uses less digits than its factorization.

21820080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90933 (or 90927 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 21820080 is about 4671.1968487744. The cubic root of 21820080 is about 279.4379883399.

Adding to 21820080 its reverse (8002812), we get a palindrome (29822892).

The spelling of 21820080 in words is "twenty-one million, eight hundred twenty thousand, eighty".