21253156 has 12 divisors (see below), whose sum is σ = 37225692. Its totient is φ = 10617248.

The previous prime is 21253121. The next prime is 21253181. The reversal of 21253156 is 65135212.

It can be written as a sum of positive squares in 2 ways, for example, as 6553600 + 14699556 = 2560^2 + 3834^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21253156.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6546 + ... + 9238.

It is an arithmetic number, because the mean of its divisors is an integer number (3102141).

Almost surely, 2^21253156 is an apocalyptic number.

It is an amenable number.

21253156 is a deficient number, since it is larger than the sum of its proper divisors (15972536).

21253156 is a wasteful number, since it uses less digits than its factorization.

21253156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4670 (or 4668 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 21253156 is about 4610.1145321998. The cubic root of 21253156 is about 276.9966244424.

Adding to 21253156 its reverse (65135212), we get a palindrome (86388368).

The spelling of 21253156 in words is "twenty-one million, two hundred fifty-three thousand, one hundred fifty-six".