21112580 has 48 divisors (see below), whose sum is σ = 46494000. Its totient is φ = 8042496.

The previous prime is 21112561. The next prime is 21112601. The reversal of 21112580 is 8521112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 7744 + 21104836 = 88^2 + 4594^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51416 + ... + 51824.

It is an arithmetic number, because the mean of its divisors is an integer number (968625).

Almost surely, 2^21112580 is an apocalyptic number.

21112580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21112580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23247000).

21112580 is an abundant number, since it is smaller than the sum of its proper divisors (25381420).

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

21112580 is a wasteful number, since it uses less digits than its factorization.

21112580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536 (or 534 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 21112580 is about 4594.8427611835. The cubic root of 21112580 is about 276.3845546131.

Adding to 21112580 its reverse (8521112), we get a palindrome (29633692).

The spelling of 21112580 in words is "twenty-one million, one hundred twelve thousand, five hundred eighty".