821540807541 has 6 divisors (see below), whose sum is σ = 1186670055350. Its totient is φ = 547693871688.

The previous prime is 821540807539. The next prime is 821540807543. The reversal of 821540807541 is 145708045128.

821540807541 is a `hidden beast` number, since 8 + 21 + 5 + 4 + 0 + 80 + 7 + 541 = 666.

It is an interprime number because it is at equal distance from previous prime (821540807539) and next prime (821540807543).

It can be written as a sum of positive squares in only one way, i.e., 650852016516 + 170688791025 = 806754^2 + 413145^2 .

It is not a de Polignac number, because 821540807541 - 2¹ = 821540807539 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821540807543) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 45641155966 + ... + 45641155983.

Almost surely, 2^821540807541 is an apocalyptic number.

It is an amenable number.

821540807541 is a deficient number, since it is larger than the sum of its proper divisors (365129247809).

821540807541 is a wasteful number, since it uses less digits than its factorization.

821540807541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91282311955 (or 91282311952 counting only the distinct ones).

The product of its (nonzero) digits is 358400, while the sum is 45.

The spelling of 821540807541 in words is "eight hundred twenty-one billion, five hundred forty million, eight hundred seven thousand, five hundred forty-one".