21111211021020 has 24 divisors (see below), whose sum is σ = 59111390859024. Its totient is φ = 5629656272256.

The previous prime is 21111211020941. The next prime is 21111211021027. The reversal of 21111211021020 is 2012011211112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111211021027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 175926758449 + ... + 175926758568.

It is an arithmetic number, because the mean of its divisors is an integer number (2462974619126).

Almost surely, 2^{21111211021020} is an apocalyptic number.

21111211021020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21111211021020 is an abundant number, since it is smaller than the sum of its proper divisors (38000179838004).

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

21111211021020 is a wasteful number, since it uses less digits than its factorization.

21111211021020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351853517029 (or 351853517027 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21111211021020 its reverse (2012011211112), we get a palindrome (23123222232132).

The spelling of 21111211021020 in words is "twenty-one trillion, one hundred eleven billion, two hundred eleven million, twenty-one thousand, twenty".