1981787511 has 16 divisors (see below), whose sum is σ = 2883916800. Its totient is φ = 1200534720.

The previous prime is 1981787473. The next prime is 1981787513. The reversal of 1981787511 is 1157871891.

It is not a de Polignac number, because 1981787511 - 2⁶ = 1981787447 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981787513) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66651 + ... + 91683.

It is an arithmetic number, because the mean of its divisors is an integer number (180244800).

Almost surely, 2^1981787511 is an apocalyptic number.

1981787511 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1981787511 is a deficient number, since it is larger than the sum of its proper divisors (902129289).

1981787511 is a wasteful number, since it uses less digits than its factorization.

1981787511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27446.

The product of its digits is 141120, while the sum is 48.

The square root of 1981787511 is about 44517.2720525416. The cubic root of 1981787511 is about 1256.0849991751.

The spelling of 1981787511 in words is "one billion, nine hundred eighty-one million, seven hundred eighty-seven thousand, five hundred eleven".