20421177021 has 48 divisors (see below), whose sum is σ = 33909902208. Its totient is φ = 11600640000.

The previous prime is 20421177017. The next prime is 20421177037. The reversal of 20421177021 is 12077112402.

It is a happy number.

It is not a de Polignac number, because 20421177021 - 2² = 20421177017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421177071) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12032845 + ... + 12034541.

It is an arithmetic number, because the mean of its divisors is an integer number (706456296).

Almost surely, 2^20421177021 is an apocalyptic number.

20421177021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20421177021 is a deficient number, since it is larger than the sum of its proper divisors (13488725187).

20421177021 is a wasteful number, since it uses less digits than its factorization.

20421177021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2722 (or 2719 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

Adding to 20421177021 its reverse (12077112402), we get a palindrome (32498289423).

The spelling of 20421177021 in words is "twenty billion, four hundred twenty-one million, one hundred seventy-seven thousand, twenty-one".