21202123021 has 16 divisors (see below), whose sum is σ = 22003809408. Its totient is φ = 20417924800.

The previous prime is 21202123013. The next prime is 21202123057. The reversal of 21202123021 is 12032120212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21202123021 - 2³ = 21202123013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202122986 and 21202123004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202123421) 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, 841791 + ... + 866611.

It is an arithmetic number, because the mean of its divisors is an integer number (1375238088).

Almost surely, 2^21202123021 is an apocalyptic number.

It is an amenable number.

21202123021 is a deficient number, since it is larger than the sum of its proper divisors (801686387).

21202123021 is a wasteful number, since it uses less digits than its factorization.

21202123021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25172.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21202123021 its reverse (12032120212), we get a palindrome (33234243233).

The spelling of 21202123021 in words is "twenty-one billion, two hundred two million, one hundred twenty-three thousand, twenty-one".