1981509223 has 4 divisors (see below), whose sum is σ = 1982042920. Its totient is φ = 1980975528.

The previous prime is 1981509217. The next prime is 1981509253. The reversal of 1981509223 is 3229051891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3229051891 = 13 ⋅248388607.

It is a cyclic number.

It is not a de Polignac number, because 1981509223 - 2¹³ = 1981501031 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981509253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261240 + ... + 268717.

It is an arithmetic number, because the mean of its divisors is an integer number (495510730).

Almost surely, 2^1981509223 is an apocalyptic number.

1981509223 is a deficient number, since it is larger than the sum of its proper divisors (533697).

1981509223 is an equidigital number, since it uses as much as digits as its factorization.

1981509223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533696.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 1981509223 is about 44514.1463245113. The cubic root of 1981509223 is about 1256.0262021306.

The spelling of 1981509223 in words is "one billion, nine hundred eighty-one million, five hundred nine thousand, two hundred twenty-three".