11621887809921 has 9 divisors (see below), whose sum is σ = 16787186053729. Its totient is φ = 7747918388436.

The previous prime is 11621887809893. The next prime is 11621887809941. The reversal of 11621887809921 is 12990878812611.

The square root of 11621887809921 is 3409089.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 11621887809921 - 2⁴³ = 2825794787713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11621887809941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 9659086 + ... + 10795448.

Almost surely, 2^{11621887809921} is an apocalyptic number.

11621887809921 is the 3409089-th square number.

11621887809921 is the 1704545-th centered octagonal number.

It is an amenable number.

11621887809921 is a deficient number, since it is larger than the sum of its proper divisors (5165298243808).

11621887809921 is an frugal number, since it uses more digits than its factorization.

11621887809921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2272732 (or 1136366 counting only the distinct ones).

The product of its (nonzero) digits is 6967296, while the sum is 63.

The spelling of 11621887809921 in words is "eleven trillion, six hundred twenty-one billion, eight hundred eighty-seven million, eight hundred nine thousand, nine hundred twenty-one".