21371236 has 6 divisors (see below), whose sum is σ = 37399670. Its totient is φ = 10685616.

The previous prime is 21371201. The next prime is 21371239. The reversal of 21371236 is 63217312.

It can be written as a sum of positive squares in only one way, i.e., 14868736 + 6502500 = 3856^2 + 2550^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21371236.

It is not an unprimeable number, because it can be changed into a prime (21371239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2671401 + ... + 2671408.

Almost surely, 2^21371236 is an apocalyptic number.

It is an amenable number.

21371236 is a deficient number, since it is larger than the sum of its proper divisors (16028434).

21371236 is a wasteful number, since it uses less digits than its factorization.

21371236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5342813 (or 5342811 counting only the distinct ones).

The product of its digits is 1512, while the sum is 25.

The square root of 21371236 is about 4622.9034166852. The cubic root of 21371236 is about 277.5086640695.

Adding to 21371236 its reverse (63217312), we get a palindrome (84588548).

It can be divided in two parts, 2 and 1371236, that multiplied together give a palindrome (2742472).

The spelling of 21371236 in words is "twenty-one million, three hundred seventy-one thousand, two hundred thirty-six".