21311225 has 24 divisors (see below), whose sum is σ = 29706432. Its totient is φ = 15048000.

The previous prime is 21311219. The next prime is 21311237. The reversal of 21311225 is 52211312.

It is a happy number.

It is not a de Polignac number, because 21311225 - 2⁶ = 21311161 is a prime.

It is a super-2 number, since 2×21311225² = 908336622001250, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6050 + ... + 8900.

It is an arithmetic number, because the mean of its divisors is an integer number (1237768).

Almost surely, 2^21311225 is an apocalyptic number.

21311225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21311225 is a deficient number, since it is larger than the sum of its proper divisors (8395207).

21311225 is a wasteful number, since it uses less digits than its factorization.

21311225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2897 (or 2892 counting only the distinct ones).

The product of its digits is 120, while the sum is 17.

The square root of 21311225 is about 4616.4082358474. The cubic root of 21311225 is about 277.2486699869.

Adding to 21311225 its reverse (52211312), we get a palindrome (73522537).

The spelling of 21311225 in words is "twenty-one million, three hundred eleven thousand, two hundred twenty-five".