21020102001 has 12 divisors (see below), whose sum is σ = 30380583220. Its totient is φ = 14004995040.

The previous prime is 21020101919. The next prime is 21020102009. The reversal of 21020102001 is 10020102012.

It can be written as a sum of positive squares in 2 ways, for example, as 11693178225 + 9326923776 = 108135^2 + 96576^2 .

It is not a de Polignac number, because 21020102001 - 2¹⁷ = 21019970929 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020102009) 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, 684670 + ... + 714711.

Almost surely, 2^21020102001 is an apocalyptic number.

It is an amenable number.

21020102001 is a deficient number, since it is larger than the sum of its proper divisors (9360481219).

21020102001 is a wasteful number, since it uses less digits than its factorization.

21020102001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1401056 (or 1401053 counting only the distinct ones).

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

Adding to 21020102001 its reverse (10020102012), we get a palindrome (31040204013).

The spelling of 21020102001 in words is "twenty-one billion, twenty million, one hundred two thousand, one".