1780639745 has 4 divisors (see below), whose sum is σ = 2136767700. Its totient is φ = 1424511792.

The previous prime is 1780639727. The next prime is 1780639769. The reversal of 1780639745 is 5479360871.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5479360871 = 43 ⋅127426997.

It can be written as a sum of positive squares in 2 ways, for example, as 914397121 + 866242624 = 30239^2 + 29432^2 .

It is a cyclic number.

It is not a de Polignac number, because 1780639745 - 2²⁰ = 1779591169 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1780639693 and 1780639702.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 178063970 + ... + 178063979.

It is an arithmetic number, because the mean of its divisors is an integer number (534191925).

Almost surely, 2^1780639745 is an apocalyptic number.

It is an amenable number.

1780639745 is a deficient number, since it is larger than the sum of its proper divisors (356127955).

1780639745 is an equidigital number, since it uses as much as digits as its factorization.

1780639745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356127954.

The product of its (nonzero) digits is 1270080, while the sum is 50.

The square root of 1780639745 is about 42197.6272437207. The cubic root of 1780639745 is about 1212.0634474749.

The spelling of 1780639745 in words is "one billion, seven hundred eighty million, six hundred thirty-nine thousand, seven hundred forty-five".