821277440 has 36 divisors (see below), whose sum is σ = 1967219184. Its totient is φ = 328510464.

The previous prime is 821277409. The next prime is 821277449. The reversal of 821277440 is 44772128.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 821277440.

It is not an unprimeable number, because it can be changed into a prime (821277449) 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, 319532 + ... + 322091.

Almost surely, 2^821277440 is an apocalyptic number.

821277440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

821277440 is an abundant number, since it is smaller than the sum of its proper divisors (1145941744).

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

821277440 is an equidigital number, since it uses as much as digits as its factorization.

821277440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 641644 (or 641630 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 35.

The square root of 821277440 is about 28657.9385162297. The cubic root of 821277440 is about 936.4759553695.

The spelling of 821277440 in words is "eight hundred twenty-one million, two hundred seventy-seven thousand, four hundred forty".