1811621781226 has 32 divisors (see below), whose sum is σ = 2890454965200. Its totient is φ = 850202196480.

The previous prime is 1811621781133. The next prime is 1811621781239. The reversal of 1811621781226 is 6221871261181.

It is a Cunningham number, because it is equal to 1345965²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 1262690453025 + 548931328201 = 1123695^2 + 740899^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2368315 + ... + 3038446.

Almost surely, 2^{1811621781226} is an apocalyptic number.

1811621781226 is a deficient number, since it is larger than the sum of its proper divisors (1078833183974).

1811621781226 is a wasteful number, since it uses less digits than its factorization.

1811621781226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5406954.

The product of its digits is 129024, while the sum is 46.

The spelling of 1811621781226 in words is "one trillion, eight hundred eleven billion, six hundred twenty-one million, seven hundred eighty-one thousand, two hundred twenty-six".