21123040 has 24 divisors (see below), whose sum is σ = 49903560. Its totient is φ = 8449152.

The previous prime is 21123029. The next prime is 21123043. The reversal of 21123040 is 4032112.

It is a self number, because there is not a number n which added to its sum of digits gives 21123040.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123043) 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 3 ways as a sum of consecutive naturals, for example, 65850 + ... + 66169.

It is an arithmetic number, because the mean of its divisors is an integer number (2079315).

Almost surely, 2^21123040 is an apocalyptic number.

21123040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21123040 is an abundant number, since it is smaller than the sum of its proper divisors (28780520).

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

21123040 is a wasteful number, since it uses less digits than its factorization.

21123040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132034 (or 132026 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21123040 is about 4595.9808528757. The cubic root of 21123040 is about 276.4301909926.

Adding to 21123040 its reverse (4032112), we get a palindrome (25155152).

The spelling of 21123040 in words is "twenty-one million, one hundred twenty-three thousand, forty".