21053745 has 24 divisors (see below), whose sum is σ = 37043136. Its totient is φ = 11059488.

The previous prime is 21053741. The next prime is 21053783. The reversal of 21053745 is 54735012.

It is a happy number.

It is not a de Polignac number, because 21053745 - 2² = 21053741 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21053741) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 477 + ... + 6506.

It is an arithmetic number, because the mean of its divisors is an integer number (1543464).

Almost surely, 2^21053745 is an apocalyptic number.

It is an amenable number.

21053745 is a deficient number, since it is larger than the sum of its proper divisors (15989391).

21053745 is a wasteful number, since it uses less digits than its factorization.

21053745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7061 (or 7058 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 21053745 is about 4588.4360080533. The cubic root of 21053745 is about 276.1275796442.

Adding to 21053745 its reverse (54735012), we get a palindrome (75788757).

The spelling of 21053745 in words is "twenty-one million, fifty-three thousand, seven hundred forty-five".