816187761 has 27 divisors (see below), whose sum is σ = 1203580651. Its totient is φ = 532983264.

The previous prime is 816187753. The next prime is 816187763. The reversal of 816187761 is 167781618.

It is a happy number.

The square root of 816187761 is 28569.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 156725361 + 659462400 = 12519^2 + 25680^2 .

It is not a de Polignac number, because 816187761 - 2³ = 816187753 is a prime.

It is a super-2 number, since 2×816187761² = 1332324922412386242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (816187763) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 7627870 + ... + 7627976.

Almost surely, 2^816187761 is an apocalyptic number.

816187761 is the 28569-th square number.

816187761 is the 14285-th centered octagonal number.

It is an amenable number.

816187761 is a deficient number, since it is larger than the sum of its proper divisors (387392890).

816187761 is an equidigital number, since it uses as much as digits as its factorization.

816187761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398 (or 199 counting only the distinct ones).

The product of its digits is 112896, while the sum is 45.

The cubic root of 816187761 is about 934.5374134681.

Multiplying 816187761 by its product of digits (112896), we get a square (92144333465856 = 9599184²).

The spelling of 816187761 in words is "eight hundred sixteen million, one hundred eighty-seven thousand, seven hundred sixty-one".