816721345 has 32 divisors (see below), whose sum is σ = 1109376000. Its totient is φ = 571764480.

The previous prime is 816721343. The next prime is 816721363. The reversal of 816721345 is 543127618.

It is not a de Polignac number, because 816721345 - 2¹ = 816721343 is a prime.

It is not an unprimeable number, because it can be changed into a prime (816721343) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 763471 + ... + 764539.

It is an arithmetic number, because the mean of its divisors is an integer number (34668000).

Almost surely, 2^816721345 is an apocalyptic number.

It is an amenable number.

816721345 is a deficient number, since it is larger than the sum of its proper divisors (292654655).

816721345 is a wasteful number, since it uses less digits than its factorization.

816721345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1593.

The product of its digits is 40320, while the sum is 37.

The square root of 816721345 is about 28578.3369880054. The cubic root of 816721345 is about 934.7410208606.

The spelling of 816721345 in words is "eight hundred sixteen million, seven hundred twenty-one thousand, three hundred forty-five".