21012120 has 48 divisors (see below), whose sum is σ = 68290560. Its totient is φ = 5603136.

The previous prime is 21012091. The next prime is 21012127. The reversal of 21012120 is 2121012.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012127) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28824 + ... + 29543.

It is an arithmetic number, because the mean of its divisors is an integer number (1422720).

Almost surely, 2^21012120 is an apocalyptic number.

21012120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012120 is an abundant number, since it is smaller than the sum of its proper divisors (47278440).

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

21012120 is a wasteful number, since it uses less digits than its factorization.

21012120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58384 (or 58377 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21012120 is about 4583.8979046222. The cubic root of 21012120 is about 275.9454838765.

Adding to 21012120 its reverse (2121012), we get a palindrome (23133132).

The spelling of 21012120 in words is "twenty-one million, twelve thousand, one hundred twenty".