21012220001 has 4 divisors (see below), whose sum is σ = 21037628592. Its totient is φ = 20986811412.

The previous prime is 21012219983. The next prime is 21012220013. The reversal of 21012220001 is 10002221012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21012220001 - 2¹⁴ = 21012203617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012270001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12703055 + ... + 12704708.

It is an arithmetic number, because the mean of its divisors is an integer number (5259407148).

Almost surely, 2^21012220001 is an apocalyptic number.

It is an amenable number.

21012220001 is a deficient number, since it is larger than the sum of its proper divisors (25408591).

21012220001 is an equidigital number, since it uses as much as digits as its factorization.

21012220001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25408590.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21012220001 its reverse (10002221012), we get a palindrome (31014441013).

The spelling of 21012220001 in words is "twenty-one billion, twelve million, two hundred twenty thousand, one".