821402491 has 16 divisors (see below), whose sum is σ = 1017413824. Its totient is φ = 645750144.

The previous prime is 821402489. The next prime is 821402501. The reversal of 821402491 is 194204128.

It is not a de Polignac number, because 821402491 - 2¹ = 821402489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (821402431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14460 + ... + 43033.

It is an arithmetic number, because the mean of its divisors is an integer number (63588364).

Almost surely, 2^821402491 is an apocalyptic number.

821402491 is a deficient number, since it is larger than the sum of its proper divisors (196011333).

821402491 is a wasteful number, since it uses less digits than its factorization.

821402491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57670.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 821402491 is about 28660.1202195664. The cubic root of 821402491 is about 936.5234834867.

The spelling of 821402491 in words is "eight hundred twenty-one million, four hundred two thousand, four hundred ninety-one".