1781021045 has 4 divisors (see below), whose sum is σ = 2137225260. Its totient is φ = 1424816832.

The previous prime is 1781021041. The next prime is 1781021059. The reversal of 1781021045 is 5401201871.

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

It can be written as a sum of positive squares in 2 ways, for example, as 844599844 + 936421201 = 29062^2 + 30601^2 .

It is a cyclic number.

It is not a de Polignac number, because 1781021045 - 2² = 1781021041 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1781020999 and 1781021017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1781021041) 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, 178102100 + ... + 178102109.

It is an arithmetic number, because the mean of its divisors is an integer number (534306315).

Almost surely, 2^1781021045 is an apocalyptic number.

It is an amenable number.

1781021045 is a deficient number, since it is larger than the sum of its proper divisors (356204215).

1781021045 is an equidigital number, since it uses as much as digits as its factorization.

1781021045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356204214.

The product of its (nonzero) digits is 2240, while the sum is 29.

The square root of 1781021045 is about 42202.1450284224. The cubic root of 1781021045 is about 1212.1499569835.

The spelling of 1781021045 in words is "one billion, seven hundred eighty-one million, twenty-one thousand, forty-five".