21012124 has 48 divisors (see below), whose sum is σ = 44049600. Its totient is φ = 8580096.

The previous prime is 21012091. The next prime is 21012127. The reversal of 21012124 is 42121012.

It is a happy number.

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 pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 91642 + ... + 91870.

It is an arithmetic number, because the mean of its divisors is an integer number (917700).

Almost surely, 2^21012124 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21012124, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22024800).

21012124 is an abundant number, since it is smaller than the sum of its proper divisors (23037476).

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

21012124 is a wasteful number, since it uses less digits than its factorization.

21012124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 382 (or 380 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21012124 is about 4583.8983409321. The cubic root of 21012124 is about 275.9455013868.

Adding to 21012124 its reverse (42121012), we get a palindrome (63133136).

It can be divided in two parts, 2101 and 2124, that added together give a square (4225 = 65²).

The spelling of 21012124 in words is "twenty-one million, twelve thousand, one hundred twenty-four".