21045740 has 12 divisors (see below), whose sum is σ = 44196096. Its totient is φ = 8418288.

The previous prime is 21045737. The next prime is 21045757. The reversal of 21045740 is 4754012.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 526124 + ... + 526163.

It is an arithmetic number, because the mean of its divisors is an integer number (3683008).

Almost surely, 2^21045740 is an apocalyptic number.

21045740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21045740 is an abundant number, since it is smaller than the sum of its proper divisors (23150356).

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

21045740 is a wasteful number, since it uses less digits than its factorization.

21045740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1052296 (or 1052294 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21045740 is about 4587.5636235370. The cubic root of 21045740 is about 276.0925790385.

Adding to 21045740 its reverse (4754012), we get a palindrome (25799752).

The spelling of 21045740 in words is "twenty-one million, forty-five thousand, seven hundred forty".