1816720129 has 9 divisors (see below), whose sum is σ = 2113674627. Its totient is φ = 1556932944.

The previous prime is 1816720123. The next prime is 1816720163. The reversal of 1816720129 is 9210276181.

The square root of 1816720129 is 42623.

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., 408969729 + 1407750400 = 20223^2 + 37520^2 .

It is not a de Polignac number, because 1816720129 - 2⁹ = 1816719617 is a prime.

It is a super-2 number, since 2×1816720129² = 6600944054227553282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1816720123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 295317 + ... + 301405.

Almost surely, 2^1816720129 is an apocalyptic number.

1816720129 is the 42623-rd square number.

1816720129 is the 21312-nd centered octagonal number.

It is an amenable number.

1816720129 is a deficient number, since it is larger than the sum of its proper divisors (296954498).

1816720129 is an frugal number, since it uses more digits than its factorization.

1816720129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12192 (or 6096 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 37.

The cubic root of 1816720129 is about 1220.1952856340.

The spelling of 1816720129 in words is "one billion, eight hundred sixteen million, seven hundred twenty thousand, one hundred twenty-nine".