1978265645 has 8 divisors (see below), whose sum is σ = 2374750104. Its totient is φ = 1582058304.

The previous prime is 1978265609. The next prime is 1978265659. The reversal of 1978265645 is 5465628791.

It can be written as a sum of positive squares in 4 ways, for example, as 1359101956 + 619163689 = 36866^2 + 24883^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1978265645 is a prime.

It is a super-3 number, since 3×1978265645³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53234 + ... + 82403.

It is an arithmetic number, because the mean of its divisors is an integer number (296843763).

Almost surely, 2^1978265645 is an apocalyptic number.

It is an amenable number.

1978265645 is a deficient number, since it is larger than the sum of its proper divisors (396484459).

1978265645 is a wasteful number, since it uses less digits than its factorization.

1978265645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138559.

The product of its digits is 3628800, while the sum is 53.

The square root of 1978265645 is about 44477.6982880185. The cubic root of 1978265645 is about 1255.3404884526.

The spelling of 1978265645 in words is "one billion, nine hundred seventy-eight million, two hundred sixty-five thousand, six hundred forty-five".