1981505729 has 32 divisors (see below), whose sum is σ = 2423070720. Its totient is φ = 1583854272.

The previous prime is 1981505719. The next prime is 1981505731. The reversal of 1981505729 is 9275051891.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-1981505729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1981505719) 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, 1054739 + ... + 1056615.

It is an arithmetic number, because the mean of its divisors is an integer number (75720960).

Almost surely, 2^1981505729 is an apocalyptic number.

It is an amenable number.

1981505729 is a deficient number, since it is larger than the sum of its proper divisors (441564991).

1981505729 is a wasteful number, since it uses less digits than its factorization.

1981505729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2069.

The product of its (nonzero) digits is 226800, while the sum is 47.

The square root of 1981505729 is about 44514.1070785431. The cubic root of 1981505729 is about 1256.0254638789.

The spelling of 1981505729 in words is "one billion, nine hundred eighty-one million, five hundred five thousand, seven hundred twenty-nine".