21316455 has 24 divisors (see below), whose sum is σ = 37056240. Its totient is φ = 11335680.

The previous prime is 21316417. The next prime is 21316459. The reversal of 21316455 is 55461312.

21316455 is a `hidden beast` number, since 2 + 13 + 1 + 645 + 5 = 666.

It is not a de Polignac number, because 21316455 - 2⁶ = 21316391 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21316459) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28476 + ... + 29214.

It is an arithmetic number, because the mean of its divisors is an integer number (1544010).

Almost surely, 2^21316455 is an apocalyptic number.

21316455 is a deficient number, since it is larger than the sum of its proper divisors (15739785).

21316455 is a wasteful number, since it uses less digits than its factorization.

21316455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1391 (or 1388 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 21316455 is about 4616.9746587999. The cubic root of 21316455 is about 277.2713480504.

Adding to 21316455 its reverse (55461312), we get a palindrome (76777767).

The spelling of 21316455 in words is "twenty-one million, three hundred sixteen thousand, four hundred fifty-five".