21021120001 has 12 divisors (see below), whose sum is σ = 24695255700. Its totient is φ = 17839701600.

The previous prime is 21021119957. The next prime is 21021120011. The reversal of 21021120001 is 10002112012.

It can be written as a sum of positive squares in 2 ways, for example, as 18166996225 + 2854123776 = 134785^2 + 53424^2 .

It is not a de Polignac number, because 21021120001 - 2²³ = 21012731393 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 21021120001.

It is not an unprimeable number, because it can be changed into a prime (21021120011) 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, 2118826 + ... + 2128723.

It is an arithmetic number, because the mean of its divisors is an integer number (2057937975).

Almost surely, 2^21021120001 is an apocalyptic number.

It is an amenable number.

21021120001 is a deficient number, since it is larger than the sum of its proper divisors (3674135699).

21021120001 is a wasteful number, since it uses less digits than its factorization.

21021120001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4247664 (or 4247657 counting only the distinct ones).

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

Adding to 21021120001 its reverse (10002112012), we get a palindrome (31023232013).

The spelling of 21021120001 in words is "twenty-one billion, twenty-one million, one hundred twenty thousand, one".