421778721 has 48 divisors (see below), whose sum is σ = 746008704. Its totient is φ = 209373696.

The previous prime is 421778719. The next prime is 421778723. The reversal of 421778721 is 127877124.

It is an interprime number because it is at equal distance from previous prime (421778719) and next prime (421778723).

It is not a de Polignac number, because 421778721 - 2¹ = 421778719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 421778721.

It is not an unprimeable number, because it can be changed into a prime (421778723) 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 47 ways as a sum of consecutive naturals, for example, 25996 + ... + 38978.

It is an arithmetic number, because the mean of its divisors is an integer number (15541848).

Almost surely, 2^421778721 is an apocalyptic number.

It is an amenable number.

421778721 is a deficient number, since it is larger than the sum of its proper divisors (324229983).

421778721 is a wasteful number, since it uses less digits than its factorization.

421778721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13030 (or 13023 counting only the distinct ones).

The product of its digits is 43904, while the sum is 39.

The square root of 421778721 is about 20537.2520313697. The cubic root of 421778721 is about 749.9429414370.

The spelling of 421778721 in words is "four hundred twenty-one million, seven hundred seventy-eight thousand, seven hundred twenty-one".