1720664977 has 4 divisors (see below), whose sum is σ = 1720748260. Its totient is φ = 1720581696.

The previous prime is 1720664941. The next prime is 1720664993. The reversal of 1720664977 is 7794660271.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7794660271 = 67 ⋅116338213.

It can be written as a sum of positive squares in 2 ways, for example, as 615833856 + 1104831121 = 24816^2 + 33239^2 .

It is a cyclic number.

It is not a de Polignac number, because 1720664977 - 2¹⁵ = 1720632209 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 1720664977.

It is not an unprimeable number, because it can be changed into a prime (1720644977) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15349 + ... + 60637.

It is an arithmetic number, because the mean of its divisors is an integer number (430187065).

Almost surely, 2^1720664977 is an apocalyptic number.

It is an amenable number.

1720664977 is a deficient number, since it is larger than the sum of its proper divisors (83283).

1720664977 is an equidigital number, since it uses as much as digits as its factorization.

1720664977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83282.

The product of its (nonzero) digits is 889056, while the sum is 49.

The square root of 1720664977 is about 41480.8989415610. The cubic root of 1720664977 is about 1198.2996698784.

The spelling of 1720664977 in words is "one billion, seven hundred twenty million, six hundred sixty-four thousand, nine hundred seventy-seven".