21571925 has 12 divisors (see below), whose sum is σ = 27473316. Its totient is φ = 16790400.

The previous prime is 21571903. The next prime is 21571933. The reversal of 21571925 is 52917512.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 97969 + 21473956 = 313^2 + 4634^2 .

It is not a de Polignac number, because 21571925 - 2¹² = 21567829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21571891 and 21571900.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10736 + ... + 12585.

It is an arithmetic number, because the mean of its divisors is an integer number (2289443).

Almost surely, 2^21571925 is an apocalyptic number.

21571925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21571925 is a deficient number, since it is larger than the sum of its proper divisors (5901391).

21571925 is a wasteful number, since it uses less digits than its factorization.

21571925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23368 (or 23363 counting only the distinct ones).

The product of its digits is 6300, while the sum is 32.

The square root of 21571925 is about 4644.5586442632. The cubic root of 21571925 is about 278.3746178815.

The spelling of 21571925 in words is "twenty-one million, five hundred seventy-one thousand, nine hundred twenty-five".