21111040 has 36 divisors (see below), whose sum is σ = 50570604. Its totient is φ = 8443904.

The previous prime is 21111029. The next prime is 21111049. The reversal of 21111040 is 4011112.

It can be written as a sum of positive squares in 2 ways, for example, as 3268864 + 17842176 = 1808^2 + 4224^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (21111049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6967 + ... + 9526.

It is an arithmetic number, because the mean of its divisors is an integer number (1404739).

Almost surely, 2^21111040 is an apocalyptic number.

21111040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111040 is an abundant number, since it is smaller than the sum of its proper divisors (29459564).

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

21111040 is an equidigital number, since it uses as much as digits as its factorization.

21111040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16514 (or 16500 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 21111040 is about 4594.6751789436. The cubic root of 21111040 is about 276.3778344087.

Adding to 21111040 its reverse (4011112), we get a palindrome (25122152).

The spelling of 21111040 in words is "twenty-one million, one hundred eleven thousand, forty".