1981777807 has 4 divisors (see below), whose sum is σ = 1982107696. Its totient is φ = 1981447920.

The previous prime is 1981777789. The next prime is 1981777813. The reversal of 1981777807 is 7087771891.

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 1981777807 - 2¹⁵ = 1981745039 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981777817) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 155763 + ... + 168004.

It is an arithmetic number, because the mean of its divisors is an integer number (495526924).

Almost surely, 2^1981777807 is an apocalyptic number.

1981777807 is a deficient number, since it is larger than the sum of its proper divisors (329889).

1981777807 is an equidigital number, since it uses as much as digits as its factorization.

1981777807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329888.

The product of its (nonzero) digits is 1382976, while the sum is 55.

The square root of 1981777807 is about 44517.1630610038. The cubic root of 1981777807 is about 1256.0829489942.

The spelling of 1981777807 in words is "one billion, nine hundred eighty-one million, seven hundred seventy-seven thousand, eight hundred seven".