21142202021 has 4 divisors (see below), whose sum is σ = 21871243500. Its totient is φ = 20413160544.

The previous prime is 21142201973. The next prime is 21142202051. The reversal of 21142202021 is 12020224112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16013637025 + 5128564996 = 126545^2 + 71614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21142202021 - 2²² = 21138007717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21142202051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364520696 + ... + 364520753.

It is an arithmetic number, because the mean of its divisors is an integer number (5467810875).

Almost surely, 2^21142202021 is an apocalyptic number.

It is an amenable number.

21142202021 is a deficient number, since it is larger than the sum of its proper divisors (729041479).

21142202021 is an equidigital number, since it uses as much as digits as its factorization.

21142202021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 729041478.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21142202021 its reverse (12020224112), we get a palindrome (33162426133).

The spelling of 21142202021 in words is "twenty-one billion, one hundred forty-two million, two hundred two thousand, twenty-one".