21211221020 has 24 divisors (see below), whose sum is σ = 48592979568. Its totient is φ = 7713171200.

The previous prime is 21211221019. The next prime is 21211221061. The reversal of 21211221020 is 2012211212.

It is a junction number, because it is equal to n+sod(n) for n = 21211220986 and 21211221004.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48207101 + ... + 48207540.

It is an arithmetic number, because the mean of its divisors is an integer number (2024707482).

Almost surely, 2^21211221020 is an apocalyptic number.

21211221020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211221020 is an abundant number, since it is smaller than the sum of its proper divisors (27381758548).

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

21211221020 is a wasteful number, since it uses less digits than its factorization.

21211221020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96414661 (or 96414659 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21211221020 its reverse (2012211212), we get a palindrome (23223432232).

The spelling of 21211221020 in words is "twenty-one billion, two hundred eleven million, two hundred twenty-one thousand, twenty".