405440640 has 448 divisors, whose sum is σ = 1605398400. Its totient is φ = 97044480.

The previous prime is 405440611. The next prime is 405440653. The reversal of 405440640 is 46044504.

It is a super-2 number, since 2×405440640² = 328764225127219200, which contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 5132121 + ... + 5132199.

Almost surely, 2^405440640 is an apocalyptic number.

405440640 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 405440640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (802699200).

405440640 is an abundant number, since it is smaller than the sum of its proper divisors (1199957760).

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

405440640 is an equidigital number, since it uses as much as digits as its factorization.

405440640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127 (or 100 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

The square root of 405440640 is about 20135.5566101362. The cubic root of 405440640 is about 740.1318489195.

The spelling of 405440640 in words is "four hundred five million, four hundred forty thousand, six hundred forty".