816213553 has 2 divisors, whose sum is σ = 816213554. Its totient is φ = 816213552.

The previous prime is 816213551. The next prime is 816213569. The reversal of 816213553 is 355312618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 807014464 + 9199089 = 28408^2 + 3033^2 .

It is a cyclic number.

It is not a de Polignac number, because 816213553 - 2¹ = 816213551 is a prime.

Together with 816213551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (816213551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 408106776 + 408106777.

It is an arithmetic number, because the mean of its divisors is an integer number (408106777).

Almost surely, 2^816213553 is an apocalyptic number.

It is an amenable number.

816213553 is a deficient number, since it is larger than the sum of its proper divisors (1).

816213553 is an equidigital number, since it uses as much as digits as its factorization.

816213553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21600, while the sum is 34.

The square root of 816213553 is about 28569.4513948028. The cubic root of 816213553 is about 934.5472573366.

It can be divided in two parts, 816 and 213553, that added together give a square (214369 = 463²).

The spelling of 816213553 in words is "eight hundred sixteen million, two hundred thirteen thousand, five hundred fifty-three".