21020012001 has 12 divisors (see below), whose sum is σ = 31486767312. Its totient is φ = 14013341172.

The previous prime is 21020011973. The next prime is 21020012059. The reversal of 21020012001 is 10021002012.

It is not a de Polignac number, because 21020012001 - 2¹¹ = 21020009953 is a prime.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21020012081) 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, 43250811 + ... + 43251296.

It is an arithmetic number, because the mean of its divisors is an integer number (2623897276).

Almost surely, 2^21020012001 is an apocalyptic number.

It is an amenable number.

21020012001 is a deficient number, since it is larger than the sum of its proper divisors (10466755311).

21020012001 is an frugal number, since it uses more digits than its factorization.

21020012001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86502122 (or 86502110 counting only the distinct ones).

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

Adding to 21020012001 its reverse (10021002012), we get a palindrome (31041014013).

The spelling of 21020012001 in words is "twenty-one billion, twenty million, twelve thousand, one".