21213025 has 48 divisors (see below), whose sum is σ = 30533760. Its totient is φ = 14515200.

The previous prime is 21213013. The next prime is 21213029. The reversal of 21213025 is 52031212.

It is not a de Polignac number, because 21213025 - 2⁵ = 21212993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21213029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 298740 + ... + 298810.

It is an arithmetic number, because the mean of its divisors is an integer number (636120).

Almost surely, 2^21213025 is an apocalyptic number.

21213025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21213025 is a deficient number, since it is larger than the sum of its proper divisors (9320735).

21213025 is a wasteful number, since it uses less digits than its factorization.

21213025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21213025 is about 4605.7599807198. The cubic root of 21213025 is about 276.8221694810.

Adding to 21213025 its reverse (52031212), we get a palindrome (73244237).

The spelling of 21213025 in words is "twenty-one million, two hundred thirteen thousand, twenty-five".