421440640 has 64 divisors (see below), whose sum is σ = 1032144120. Its totient is φ = 164454400.

The previous prime is 421440611. The next prime is 421440641. The reversal of 421440640 is 46044124.

It can be written as a sum of positive squares in 4 ways, for example, as 90782784 + 330657856 = 9528^2 + 18184^2 .

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×421440640² = 355224426087219200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (421440641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18210 + ... + 34270.

Almost surely, 2^421440640 is an apocalyptic number.

421440640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 421440640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (516072060).

421440640 is an abundant number, since it is smaller than the sum of its proper divisors (610703480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

421440640 is a wasteful number, since it uses less digits than its factorization.

421440640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16121 (or 16109 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 25.

The square root of 421440640 is about 20529.0194602665. The cubic root of 421440640 is about 749.7425130923.

Adding to 421440640 its reverse (46044124), we get a palindrome (467484764).

The spelling of 421440640 in words is "four hundred twenty-one million, four hundred forty thousand, six hundred forty".