421805781 has 12 divisors (see below), whose sum is σ = 609562252. Its totient is φ = 281071296.

The previous prime is 421805779. The next prime is 421805801. The reversal of 421805781 is 187508124.

421805781 is a `hidden beast` number, since 4 + 2 + 1 + 80 + 578 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 85266756 + 336539025 = 9234^2 + 18345^2 .

It is not a de Polignac number, because 421805781 - 2¹ = 421805779 is a prime.

It is a super-2 number, since 2×421805781² = 355840233770039922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421805731) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11535 + ... + 31251.

Almost surely, 2^421805781 is an apocalyptic number.

It is an amenable number.

421805781 is a deficient number, since it is larger than the sum of its proper divisors (187756471).

421805781 is a wasteful number, since it uses less digits than its factorization.

421805781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22100 (or 22097 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

The square root of 421805781 is about 20537.9108236451. The cubic root of 421805781 is about 749.9589790898.

It can be divided in two parts, 42180 and 5781, that added together give a square (47961 = 219²).

The spelling of 421805781 in words is "four hundred twenty-one million, eight hundred five thousand, seven hundred eighty-one".