21202001001 has 12 divisors (see below), whose sum is σ = 30636272628. Its totient is φ = 14129516544.

The previous prime is 21202000997. The next prime is 21202001003. The reversal of 21202001001 is 10010020212.

It can be written as a sum of positive squares in 2 ways, for example, as 10281960000 + 10920041001 = 101400^2 + 104499^2 .

It is not a de Polignac number, because 21202001001 - 2² = 21202000997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21202001003) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 403080 + ... + 452633.

It is an arithmetic number, because the mean of its divisors is an integer number (2553022719).

Almost surely, 2^21202001001 is an apocalyptic number.

It is an amenable number.

21202001001 is a deficient number, since it is larger than the sum of its proper divisors (9434271627).

21202001001 is a wasteful number, since it uses less digits than its factorization.

21202001001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 858472 (or 858469 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21202001001 its reverse (10010020212), we get a palindrome (31212021213).

The spelling of 21202001001 in words is "twenty-one billion, two hundred two million, one thousand, one".