1981791525 has 72 divisors (see below), whose sum is σ = 3900461664. Its totient is φ = 884822400.

The previous prime is 1981791509. The next prime is 1981791557. The reversal of 1981791525 is 5251971891.

It is not a de Polignac number, because 1981791525 - 2⁴ = 1981791509 is a prime.

It is a congruent number.

It is an unprimeable number.

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 71 ways as a sum of consecutive naturals, for example, 151755 + ... + 164295.

Almost surely, 2^1981791525 is an apocalyptic number.

1981791525 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1981791525 is a deficient number, since it is larger than the sum of its proper divisors (1918670139).

1981791525 is a wasteful number, since it uses less digits than its factorization.

1981791525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12611 (or 12599 counting only the distinct ones).

The product of its digits is 226800, while the sum is 48.

The square root of 1981791525 is about 44517.3171361438. The cubic root of 1981791525 is about 1256.0858472179.

The spelling of 1981791525 in words is "one billion, nine hundred eighty-one million, seven hundred ninety-one thousand, five hundred twenty-five".