21185060991 has 16 divisors (see below), whose sum is σ = 29269532160. Its totient is φ = 13620297600.

The previous prime is 21185060987. The next prime is 21185061031. The reversal of 21185060991 is 19906058112.

It is not a de Polignac number, because 21185060991 - 2² = 21185060987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185060951) 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, 1029210 + ... + 1049591.

It is an arithmetic number, because the mean of its divisors is an integer number (1829345760).

Almost surely, 2^21185060991 is an apocalyptic number.

21185060991 is a deficient number, since it is larger than the sum of its proper divisors (8084471169).

21185060991 is a wasteful number, since it uses less digits than its factorization.

21185060991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2078926.

The product of its (nonzero) digits is 38880, while the sum is 42.

The spelling of 21185060991 in words is "twenty-one billion, one hundred eighty-five million, sixty thousand, nine hundred ninety-one".