421021665 has 96 divisors (see below), whose sum is σ = 809792640. Its totient is φ = 207432576.

The previous prime is 421021651. The next prime is 421021669. The reversal of 421021665 is 566120124.

It is not a de Polignac number, because 421021665 - 2¹¹ = 421019617 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421021669) 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 95 ways as a sum of consecutive naturals, for example, 2582874 + ... + 2583036.

It is an arithmetic number, because the mean of its divisors is an integer number (8435340).

Almost surely, 2^421021665 is an apocalyptic number.

421021665 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

421021665 is a deficient number, since it is larger than the sum of its proper divisors (388770975).

421021665 is a wasteful number, since it uses less digits than its factorization.

421021665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268 (or 243 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 421021665 is about 20518.8124656375. The cubic root of 421021665 is about 749.4939786667.

Adding to 421021665 its reverse (566120124), we get a palindrome (987141789).

The spelling of 421021665 in words is "four hundred twenty-one million, twenty-one thousand, six hundred sixty-five".