821940899899 has 4 divisors (see below), whose sum is σ = 939361028464. Its totient is φ = 704520771336.

The previous prime is 821940899893. The next prime is 821940899921. The reversal of 821940899899 is 998998049128.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 821940899899 - 2¹⁵ = 821940867131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821940899893) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58710064272 + ... + 58710064285.

It is an arithmetic number, because the mean of its divisors is an integer number (234840257116).

Almost surely, 2^821940899899 is an apocalyptic number.

821940899899 is a deficient number, since it is larger than the sum of its proper divisors (117420128565).

821940899899 is a wasteful number, since it uses less digits than its factorization.

821940899899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117420128564.

The product of its (nonzero) digits is 241864704, while the sum is 76.

The spelling of 821940899899 in words is "eight hundred twenty-one billion, nine hundred forty million, eight hundred ninety-nine thousand, eight hundred ninety-nine".