21201210001 has 4 divisors (see below), whose sum is σ = 21226971712. Its totient is φ = 21175448292.

The previous prime is 21201209993. The next prime is 21201210007. The reversal of 21201210001 is 10001210212.

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 21201210001 - 2³ = 21201209993 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21201210001.

It is not an unprimeable number, because it can be changed into a prime (21201210007) 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, 12879621 + ... + 12881266.

It is an arithmetic number, because the mean of its divisors is an integer number (5306742928).

Almost surely, 2^21201210001 is an apocalyptic number.

It is an amenable number.

21201210001 is a deficient number, since it is larger than the sum of its proper divisors (25761711).

21201210001 is an equidigital number, since it uses as much as digits as its factorization.

21201210001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25761710.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21201210001 its reverse (10001210212), we get a palindrome (31202420213).

It can be divided in two parts, 2120 and 1210001, that added together give a palindrome (1212121).

The spelling of 21201210001 in words is "twenty-one billion, two hundred one million, two hundred ten thousand, one".