1980651643 has 4 divisors (see below), whose sum is σ = 1981635640. Its totient is φ = 1979667648.

The previous prime is 1980651613. The next prime is 1980651661. The reversal of 1980651643 is 3461560891.

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 1980651643 - 2²⁹ = 1443780731 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1980651643.

It is not an unprimeable number, because it can be changed into a prime (1980651613) 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, 488973 + ... + 493006.

It is an arithmetic number, because the mean of its divisors is an integer number (495408910).

Almost surely, 2^1980651643 is an apocalyptic number.

1980651643 is a deficient number, since it is larger than the sum of its proper divisors (983997).

1980651643 is an equidigital number, since it uses as much as digits as its factorization.

1980651643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983996.

The product of its (nonzero) digits is 155520, while the sum is 43.

The square root of 1980651643 is about 44504.5126138912. The cubic root of 1980651643 is about 1255.8449769029.

The spelling of 1980651643 in words is "one billion, nine hundred eighty million, six hundred fifty-one thousand, six hundred forty-three".