21053825 has 12 divisors (see below), whose sum is σ = 28115388. Its totient is φ = 15547200.

The previous prime is 21053783. The next prime is 21053831. The reversal of 21053825 is 52835012.

It can be written as a sum of positive squares in 6 ways, for example, as 2999824 + 18054001 = 1732^2 + 4249^2 .

It is not a de Polignac number, because 21053825 - 2¹² = 21049729 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21053794 and 21053803.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32066 + ... + 32715.

It is an arithmetic number, because the mean of its divisors is an integer number (2342949).

Almost surely, 2^21053825 is an apocalyptic number.

21053825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21053825 is a deficient number, since it is larger than the sum of its proper divisors (7061563).

21053825 is a wasteful number, since it uses less digits than its factorization.

21053825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64804 (or 64799 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 21053825 is about 4588.4447256124. Note that the first 3 decimals coincide. The cubic root of 21053825 is about 276.1279293868.

Adding to 21053825 its reverse (52835012), we get a palindrome (73888837).

The spelling of 21053825 in words is "twenty-one million, fifty-three thousand, eight hundred twenty-five".