21011025 has 48 divisors (see below), whose sum is σ = 41013248. Its totient is φ = 9288000.

The previous prime is 21011009. The next prime is 21011033. The reversal of 21011025 is 52011012.

It is not a de Polignac number, because 21011025 - 2⁴ = 21011009 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011025.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 15630 + ... + 16920.

Almost surely, 2^21011025 is an apocalyptic number.

21011025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21011025 is a deficient number, since it is larger than the sum of its proper divisors (20002223).

21011025 is a wasteful number, since it uses less digits than its factorization.

21011025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1342 (or 1337 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21011025 is about 4583.7784632331. The cubic root of 21011025 is about 275.9406903645.

Adding to 21011025 its reverse (52011012), we get a palindrome (73022037).

The spelling of 21011025 in words is "twenty-one million, eleven thousand, twenty-five".