21451336 has 8 divisors (see below), whose sum is σ = 40221270. Its totient is φ = 10725664.

The previous prime is 21451319. The next prime is 21451343. The reversal of 21451336 is 63315412.

It can be written as a sum of positive squares in only one way, i.e., 18232900 + 3218436 = 4270^2 + 1794^2 .

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

It is a self number, because there is not a number n which added to its sum of digits gives 21451336.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1340701 + ... + 1340716.

Almost surely, 2^21451336 is an apocalyptic number.

It is an amenable number.

21451336 is a deficient number, since it is larger than the sum of its proper divisors (18769934).

21451336 is a wasteful number, since it uses less digits than its factorization.

21451336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2681423 (or 2681419 counting only the distinct ones).

The product of its digits is 2160, while the sum is 25.

The square root of 21451336 is about 4631.5587009127. The cubic root of 21451336 is about 277.8549352714.

Adding to 21451336 its reverse (63315412), we get a palindrome (84766748).

It can be divided in two parts, 2145 and 1336, that added together give a square (3481 = 59²).

The spelling of 21451336 in words is "twenty-one million, four hundred fifty-one thousand, three hundred thirty-six".