420005721 has 4 divisors (see below), whose sum is σ = 560007632. Its totient is φ = 280003812.

The previous prime is 420005711. The next prime is 420005743. The reversal of 420005721 is 127500024.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 420005721 - 2⁶ = 420005657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (420005711) 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 3 ways as a sum of consecutive naturals, for example, 70000951 + ... + 70000956.

It is an arithmetic number, because the mean of its divisors is an integer number (140001908).

Almost surely, 2^420005721 is an apocalyptic number.

It is an amenable number.

420005721 is a deficient number, since it is larger than the sum of its proper divisors (140001911).

420005721 is a wasteful number, since it uses less digits than its factorization.

420005721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140001910.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 420005721 is about 20494.0411095518. The cubic root of 420005721 is about 748.8906390111.

Adding to 420005721 its reverse (127500024), we get a palindrome (547505745).

The spelling of 420005721 in words is "four hundred twenty million, five thousand, seven hundred twenty-one".