821404491 has 8 divisors (see below), whose sum is σ = 1095453840. Its totient is φ = 547479072.

The previous prime is 821404483. The next prime is 821404499. The reversal of 821404491 is 194404128.

It is an interprime number because it is at equal distance from previous prime (821404483) and next prime (821404499).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 821404491 - 2³ = 821404483 is a prime.

It is not an unprimeable number, because it can be changed into a prime (821404499) 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, 14220 + ... + 42953.

It is an arithmetic number, because the mean of its divisors is an integer number (136931730).

Almost surely, 2^821404491 is an apocalyptic number.

821404491 is a deficient number, since it is larger than the sum of its proper divisors (274049349).

821404491 is a wasteful number, since it uses less digits than its factorization.

821404491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61965.

The product of its (nonzero) digits is 9216, while the sum is 33.

The square root of 821404491 is about 28660.1551112341. The cubic root of 821404491 is about 936.5242435873.

The spelling of 821404491 in words is "eight hundred twenty-one million, four hundred four thousand, four hundred ninety-one".