21097925 has 12 divisors (see below), whose sum is σ = 26235300. Its totient is φ = 16830720.

The previous prime is 21097919. The next prime is 21097927. The reversal of 21097925 is 52979012.

It can be written as a sum of positive squares in 6 ways, for example, as 829921 + 20268004 = 911^2 + 4502^2 .

It is not a de Polignac number, because 21097925 - 2⁶ = 21097861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21097927) 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 11 ways as a sum of consecutive naturals, for example, 9851 + ... + 11799.

It is an arithmetic number, because the mean of its divisors is an integer number (2186275).

Almost surely, 2^21097925 is an apocalyptic number.

21097925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21097925 is a deficient number, since it is larger than the sum of its proper divisors (5137375).

21097925 is a wasteful number, since it uses less digits than its factorization.

21097925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2392 (or 2387 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 35.

The square root of 21097925 is about 4593.2477616606. The cubic root of 21097925 is about 276.3205903291.

It can be divided in two parts, 21097 and 925, that added together give a palindrome (22022).

The spelling of 21097925 in words is "twenty-one million, ninety-seven thousand, nine hundred twenty-five".