1819861878649 has 8 divisors (see below), whose sum is σ = 1864803565800. Its totient is φ = 1774946611200.

The previous prime is 1819861878643. The next prime is 1819861878713. The reversal of 1819861878649 is 9468781689181.

It can be written as a sum of positive squares in 4 ways, for example, as 28855137424 + 1791006741225 = 169868^2 + 1338285^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1819861878649 - 2⁷ = 1819861878521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1819861878643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6465424 + ... + 6741025.

It is an arithmetic number, because the mean of its divisors is an integer number (233100445725).

Almost surely, 2^{1819861878649} is an apocalyptic number.

It is an amenable number.

1819861878649 is a deficient number, since it is larger than the sum of its proper divisors (44941687151).

1819861878649 is a wasteful number, since it uses less digits than its factorization.

1819861878649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13209851.

The product of its digits is 334430208, while the sum is 76.

The spelling of 1819861878649 in words is "one trillion, eight hundred nineteen billion, eight hundred sixty-one million, eight hundred seventy-eight thousand, six hundred forty-nine".