21121045500 has 48 divisors (see below), whose sum is σ = 61504488864. Its totient is φ = 5632278400.

The previous prime is 21121045471. The next prime is 21121045507. The reversal of 21121045500 is 554012112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121045507) 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, 7038849 + ... + 7041848.

It is an arithmetic number, because the mean of its divisors is an integer number (1281343518).

Almost surely, 2^21121045500 is an apocalyptic number.

21121045500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121045500 is an abundant number, since it is smaller than the sum of its proper divisors (40383443364).

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

21121045500 is a wasteful number, since it uses less digits than its factorization.

21121045500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14080719 (or 14080707 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 21.

Adding to 21121045500 its reverse (554012112), we get a palindrome (21675057612).

The spelling of 21121045500 in words is "twenty-one billion, one hundred twenty-one million, forty-five thousand, five hundred".