21155011100 has 36 divisors (see below), whose sum is σ = 45912821808. Its totient is φ = 8460816000.

The previous prime is 21155011067. The next prime is 21155011153. The reversal of 21155011100 is 111055112.

It is a super-2 number, since 2×21155011100² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1174160 + ... + 1192040.

Almost surely, 2^21155011100 is an apocalyptic number.

21155011100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21155011100 is an abundant number, since it is smaller than the sum of its proper divisors (24757810708).

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

21155011100 is a wasteful number, since it uses less digits than its factorization.

21155011100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29726 (or 29719 counting only the distinct ones).

The product of its (nonzero) digits is 50, while the sum is 17.

Adding to 21155011100 its reverse (111055112), we get a palindrome (21266066212).

The spelling of 21155011100 in words is "twenty-one billion, one hundred fifty-five million, eleven thousand, one hundred".