21012580 has 24 divisors (see below), whose sum is σ = 44388792. Its totient is φ = 8355072.

The previous prime is 21012569. The next prime is 21012581. The reversal of 21012580 is 8521012.

It can be written as a sum of positive squares in 4 ways, for example, as 10810944 + 10201636 = 3288^2 + 3194^2 .

It is not an unprimeable number, because it can be changed into a prime (21012581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 424 + ... + 6496.

It is an arithmetic number, because the mean of its divisors is an integer number (1849533).

Almost surely, 2^21012580 is an apocalyptic number.

21012580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012580 is an abundant number, since it is smaller than the sum of its proper divisors (23376212).

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

21012580 is a wasteful number, since it uses less digits than its factorization.

21012580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6255 (or 6253 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 21012580 is about 4583.9480799852. The cubic root of 21012580 is about 275.9474975397.

Adding to 21012580 its reverse (8521012), we get a palindrome (29533592).

It can be divided in two parts, 210125 and 80, that multiplied together give a square (16810000 = 4100²).

The spelling of 21012580 in words is "twenty-one million, twelve thousand, five hundred eighty".