21253166 has 24 divisors (see below), whose sum is σ = 36184512. Its totient is φ = 9345600.

The previous prime is 21253121. The next prime is 21253181. The reversal of 21253166 is 66135212.

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6086 + ... + 8918.

It is an arithmetic number, because the mean of its divisors is an integer number (1507688).

Almost surely, 2^21253166 is an apocalyptic number.

21253166 is a deficient number, since it is larger than the sum of its proper divisors (14931346).

21253166 is a wasteful number, since it uses less digits than its factorization.

21253166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2888 (or 2877 counting only the distinct ones).

The product of its digits is 2160, while the sum is 26.

The square root of 21253166 is about 4610.1156167714. The cubic root of 21253166 is about 276.9966678864.

Adding to 21253166 its reverse (66135212), we get a palindrome (87388378).

The spelling of 21253166 in words is "twenty-one million, two hundred fifty-three thousand, one hundred sixty-six".