21108536 has 8 divisors (see below), whose sum is σ = 39578520. Its totient is φ = 10554264.

The previous prime is 21108497. The next prime is 21108539. The reversal of 21108536 is 63580112.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21108539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1319276 + ... + 1319291.

It is an arithmetic number, because the mean of its divisors is an integer number (4947315).

Almost surely, 2^21108536 is an apocalyptic number.

It is an amenable number.

21108536 is a deficient number, since it is larger than the sum of its proper divisors (18469984).

21108536 is a wasteful number, since it uses less digits than its factorization.

21108536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2638573 (or 2638569 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21108536 is about 4594.4026815246. The cubic root of 21108536 is about 276.3669068330.

Adding to 21108536 its reverse (63580112), we get a palindrome (84688648).

The spelling of 21108536 in words is "twenty-one million, one hundred eight thousand, five hundred thirty-six".