21210020001 has 12 divisors (see below), whose sum is σ = 31383932580. Its totient is φ = 13795134720.

The previous prime is 21210019993. The next prime is 21210020003. The reversal of 21210020001 is 10002001212.

It can be written as a sum of positive squares in 2 ways, for example, as 889232400 + 20320787601 = 29820^2 + 142551^2 .

It is not a de Polignac number, because 21210020001 - 2³ = 21210019993 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 (21210020003) 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, 28739496 + ... + 28740233.

It is an arithmetic number, because the mean of its divisors is an integer number (2615327715).

Almost surely, 2^21210020001 is an apocalyptic number.

It is an amenable number.

21210020001 is a deficient number, since it is larger than the sum of its proper divisors (10173912579).

21210020001 is a wasteful number, since it uses less digits than its factorization.

21210020001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57479776 (or 57479773 counting only the distinct ones).

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

Adding to 21210020001 its reverse (10002001212), we get a palindrome (31212021213).

The spelling of 21210020001 in words is "twenty-one billion, two hundred ten million, twenty thousand, one".