21053040 has 40 divisors (see below), whose sum is σ = 65265168. Its totient is φ = 5614080.

The previous prime is 21053017. The next prime is 21053041. The reversal of 21053040 is 4035012.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053041) 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 7 ways as a sum of consecutive naturals, for example, 43621 + ... + 44100.

Almost surely, 2^21053040 is an apocalyptic number.

21053040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21053040 is an abundant number, since it is smaller than the sum of its proper divisors (44212128).

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

21053040 is a wasteful number, since it uses less digits than its factorization.

21053040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87737 (or 87731 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21053040 is about 4588.3591838478. The cubic root of 21053040 is about 276.1244974987.

Adding to 21053040 its reverse (4035012), we get a palindrome (25088052).

The spelling of 21053040 in words is "twenty-one million, fifty-three thousand, forty".