421781405809 has 9 divisors (see below), whose sum is σ = 423795787531. Its totient is φ = 419776562920.

The previous prime is 421781405797. The next prime is 421781405813. The reversal of 421781405809 is 908504187124.

The square root of 421781405809 is 649447.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 235761715809 + 186019690000 = 485553^2 + 431300^2 .

It is not a de Polignac number, because 421781405809 - 2¹³ = 421781397617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (421781405209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 147423039 + ... + 147425899.

Almost surely, 2^421781405809 is an apocalyptic number.

421781405809 is the 649447-th square number.

421781405809 is the 324724-th centered octagonal number.

It is an amenable number.

421781405809 is a deficient number, since it is larger than the sum of its proper divisors (2014381722).

421781405809 is an frugal number, since it uses more digits than its factorization.

421781405809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6176 (or 3088 counting only the distinct ones).

The product of its (nonzero) digits is 645120, while the sum is 49.

Multiplying 421781405809 by its sum of digits (49), we get a square (20667288884641 = 4546129²).

The spelling of 421781405809 in words is "four hundred twenty-one billion, seven hundred eighty-one million, four hundred five thousand, eight hundred nine".