21901025 has 6 divisors (see below), whose sum is σ = 27157302. Its totient is φ = 17520800.

The previous prime is 21901021. The next prime is 21901051. The reversal of 21901025 is 52010912.

It can be written as a sum of positive squares in 3 ways, for example, as 73441 + 21827584 = 271^2 + 4672^2 .

It is not a de Polignac number, because 21901025 - 2² = 21901021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21900988 and 21901006.

It is not an unprimeable number, because it can be changed into a prime (21901021) 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 5 ways as a sum of consecutive naturals, for example, 437996 + ... + 438045.

It is an arithmetic number, because the mean of its divisors is an integer number (4526217).

Almost surely, 2^21901025 is an apocalyptic number.

21901025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21901025 is a deficient number, since it is larger than the sum of its proper divisors (5256277).

21901025 is an equidigital number, since it uses as much as digits as its factorization.

21901025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 876051 (or 876046 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 21901025 is about 4679.8530959850. The cubic root of 21901025 is about 279.7831015836.

Adding to 21901025 its reverse (52010912), we get a palindrome (73911937).

The spelling of 21901025 in words is "twenty-one million, nine hundred one thousand, twenty-five".