821240909121 has 16 divisors (see below), whose sum is σ = 1098801809280. Its totient is φ = 545587236480.

The previous prime is 821240909113. The next prime is 821240909123. The reversal of 821240909121 is 121909042128.

It is not a de Polignac number, because 821240909121 - 2³ = 821240909113 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 821240909121.

It is not an unprimeable number, because it can be changed into a prime (821240909123) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18604845 + ... + 18648933.

It is an arithmetic number, because the mean of its divisors is an integer number (68675113080).

Almost surely, 2^821240909121 is an apocalyptic number.

It is an amenable number.

821240909121 is a deficient number, since it is larger than the sum of its proper divisors (277560900159).

821240909121 is a wasteful number, since it uses less digits than its factorization.

821240909121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65576.

The product of its (nonzero) digits is 20736, while the sum is 39.

The spelling of 821240909121 in words is "eight hundred twenty-one billion, two hundred forty million, nine hundred nine thousand, one hundred twenty-one".