1971981559 has 4 divisors (see below), whose sum is σ = 1979100904. Its totient is φ = 1964862216.

The previous prime is 1971981541. The next prime is 1971981569. The reversal of 1971981559 is 9551891791.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1971981559 - 2¹¹ = 1971979511 is a prime.

It is a super-2 number, since 2×1971981559² = 7777422538072140962, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1971981569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3559257 + ... + 3559810.

It is an arithmetic number, because the mean of its divisors is an integer number (494775226).

Almost surely, 2^1971981559 is an apocalyptic number.

1971981559 is a deficient number, since it is larger than the sum of its proper divisors (7119345).

1971981559 is an equidigital number, since it uses as much as digits as its factorization.

1971981559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7119344.

The product of its digits is 1020600, while the sum is 55.

The square root of 1971981559 is about 44406.9989866462. The cubic root of 1971981559 is about 1254.0098556781.

The spelling of 1971981559 in words is "one billion, nine hundred seventy-one million, nine hundred eighty-one thousand, five hundred fifty-nine".