21320236 has 12 divisors (see below), whose sum is σ = 42640528. Its totient is φ = 9137232.

The previous prime is 21320213. The next prime is 21320239. The reversal of 21320236 is 63202312.

21320236 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21320239) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 380691 + ... + 380746.

Almost surely, 2^21320236 is an apocalyptic number.

It is an amenable number.

21320236 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21320236 is a wasteful number, since it uses less digits than its factorization.

21320236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 761448 (or 761446 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 19.

The square root of 21320236 is about 4617.3841079122. The cubic root of 21320236 is about 277.2877407228.

Adding to 21320236 its reverse (63202312), we get a palindrome (84522548).

It can be divided in two parts, 213 and 20236, that added together give a square (20449 = 143²).

The spelling of 21320236 in words is "twenty-one million, three hundred twenty thousand, two hundred thirty-six".