161781447826 has 4 divisors (see below), whose sum is σ = 242672171742. Its totient is φ = 80890723912.

The previous prime is 161781447823. The next prime is 161781447833. The reversal of 161781447826 is 628744187161.

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

It can be written as a sum of positive squares in only one way, i.e., 132557887225 + 29223560601 = 364085^2 + 170949^2 .

It is not an unprimeable number, because it can be changed into a prime (161781447823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40445361955 + ... + 40445361958.

Almost surely, 2^161781447826 is an apocalyptic number.

161781447826 is a deficient number, since it is larger than the sum of its proper divisors (80890723916).

161781447826 is an equidigital number, since it uses as much as digits as its factorization.

161781447826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80890723915.

The product of its digits is 3612672, while the sum is 55.

The spelling of 161781447826 in words is "one hundred sixty-one billion, seven hundred eighty-one million, four hundred forty-seven thousand, eight hundred twenty-six".