1816921523 has 4 divisors (see below), whose sum is σ = 1817006880. Its totient is φ = 1816836168.

The previous prime is 1816921517. The next prime is 1816921573. The reversal of 1816921523 is 3251296181.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 3251296181 = 7 ⋅464470883.

It is a cyclic number.

It is not a de Polignac number, because 1816921523 - 2⁴ = 1816921507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1816921573) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18161 + ... + 62957.

It is an arithmetic number, because the mean of its divisors is an integer number (454251720).

Almost surely, 2^1816921523 is an apocalyptic number.

1816921523 is a deficient number, since it is larger than the sum of its proper divisors (85357).

1816921523 is an equidigital number, since it uses as much as digits as its factorization.

1816921523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85356.

The product of its digits is 25920, while the sum is 38.

The square root of 1816921523 is about 42625.3624383418. The cubic root of 1816921523 is about 1220.2403725511.

The spelling of 1816921523 in words is "one billion, eight hundred sixteen million, nine hundred twenty-one thousand, five hundred twenty-three".