21191210920 has 64 divisors (see below), whose sum is σ = 52475221440. Its totient is φ = 7637683200.

The previous prime is 21191210897. The next prime is 21191210921. The reversal of 21191210920 is 2901219112.

It is not an unprimeable number, because it can be changed into a prime (21191210921) 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, 163386 + ... + 262825.

It is an arithmetic number, because the mean of its divisors is an integer number (819925335).

Almost surely, 2^21191210920 is an apocalyptic number.

21191210920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21191210920 is an abundant number, since it is smaller than the sum of its proper divisors (31284010520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21191210920 is a wasteful number, since it uses less digits than its factorization.

21191210920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 426346 (or 426342 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 28.

The spelling of 21191210920 in words is "twenty-one billion, one hundred ninety-one million, two hundred ten thousand, nine hundred twenty".