420381721 has 4 divisors (see below), whose sum is σ = 420429492. Its totient is φ = 420333952.

The previous prime is 420381713. The next prime is 420381737. The reversal of 420381721 is 127183024.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 268599321 + 151782400 = 16389^2 + 12320^2 .

It is a cyclic number.

It is not a de Polignac number, because 420381721 - 2³ = 420381713 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 420381721.

It is not an unprimeable number, because it can be changed into a prime (420391721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6436 + ... + 29701.

It is an arithmetic number, because the mean of its divisors is an integer number (105107373).

Almost surely, 2^420381721 is an apocalyptic number.

It is an amenable number.

420381721 is a deficient number, since it is larger than the sum of its proper divisors (47771).

420381721 is a wasteful number, since it uses less digits than its factorization.

420381721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47770.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 420381721 is about 20503.2124556129. The cubic root of 420381721 is about 749.1140477896.

The spelling of 420381721 in words is "four hundred twenty million, three hundred eighty-one thousand, seven hundred twenty-one".