21225931 has 4 divisors (see below), whose sum is σ = 21432112. Its totient is φ = 21019752.

The previous prime is 21225881. The next prime is 21225943. The reversal of 21225931 is 13952212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21225931 - 2¹¹ = 21223883 is a prime.

It is a super-2 number, since 2×21225931² = 901080293633522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21225896 and 21225905.

It is not an unprimeable number, because it can be changed into a prime (21225431) 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 3 ways as a sum of consecutive naturals, for example, 102936 + ... + 103141.

It is an arithmetic number, because the mean of its divisors is an integer number (5358028).

Almost surely, 2^21225931 is an apocalyptic number.

21225931 is a deficient number, since it is larger than the sum of its proper divisors (206181).

21225931 is a wasteful number, since it uses less digits than its factorization.

21225931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206180.

The product of its digits is 1080, while the sum is 25.

The square root of 21225931 is about 4607.1608393890. The cubic root of 21225931 is about 276.8782976166.

The spelling of 21225931 in words is "twenty-one million, two hundred twenty-five thousand, nine hundred thirty-one".