21013025 has 24 divisors (see below), whose sum is σ = 29102304. Its totient is φ = 14918400.

The previous prime is 21013021. The next prime is 21013043. The reversal of 21013025 is 52031012.

It is a happy number.

It is not a de Polignac number, because 21013025 - 2² = 21013021 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21013021) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 10937 + ... + 12713.

It is an arithmetic number, because the mean of its divisors is an integer number (1212596).

Almost surely, 2^21013025 is an apocalyptic number.

21013025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21013025 is a deficient number, since it is larger than the sum of its proper divisors (8089279).

21013025 is a wasteful number, since it uses less digits than its factorization.

21013025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1841 (or 1836 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21013025 is about 4583.9966186724. The cubic root of 21013025 is about 275.9494455120.

Adding to 21013025 its reverse (52031012), we get a palindrome (73044037).

The spelling of 21013025 in words is "twenty-one million, thirteen thousand, twenty-five".