21212080 has 20 divisors (see below), whose sum is σ = 49318272. Its totient is φ = 8484800.

The previous prime is 21212077. The next prime is 21212083. The reversal of 21212080 is 8021212.

It is an interprime number because it is at equal distance from previous prime (21212077) and next prime (21212083).

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (21212083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 132496 + ... + 132655.

Almost surely, 2^21212080 is an apocalyptic number.

21212080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212080 is an abundant number, since it is smaller than the sum of its proper divisors (28106192).

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

21212080 is a wasteful number, since it uses less digits than its factorization.

21212080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265164 (or 265158 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 21212080 is about 4605.6573906447. The cubic root of 21212080 is about 276.8180587859.

Adding to 21212080 its reverse (8021212), we get a palindrome (29233292).

The spelling of 21212080 in words is "twenty-one million, two hundred twelve thousand, eighty".