21321236 has 6 divisors (see below), whose sum is σ = 37312170. Its totient is φ = 10660616.

The previous prime is 21321217. The next prime is 21321263. The reversal of 21321236 is 63212312.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 14592400 + 6728836 = 3820^2 + 2594^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2665151 + ... + 2665158.

It is an arithmetic number, because the mean of its divisors is an integer number (6218695).

Almost surely, 2^21321236 is an apocalyptic number.

It is an amenable number.

21321236 is a deficient number, since it is larger than the sum of its proper divisors (15990934).

21321236 is a wasteful number, since it uses less digits than its factorization.

21321236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5330313 (or 5330311 counting only the distinct ones).

The product of its digits is 432, while the sum is 20.

The square root of 21321236 is about 4617.4923930636. The cubic root of 21321236 is about 277.2920759376.

Adding to 21321236 its reverse (63212312), we get a palindrome (84533548).

The spelling of 21321236 in words is "twenty-one million, three hundred twenty-one thousand, two hundred thirty-six".