21001212212001 has 16 divisors (see below), whose sum is σ = 32682737547264. Its totient is φ = 11745358804944.

The previous prime is 21001212211999. The next prime is 21001212212011. The reversal of 21001212212001 is 10021221210012.

It is not a de Polignac number, because 21001212212001 - 2¹ = 21001212211999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21001212212011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10638910975 + ... + 10638912948.

It is an arithmetic number, because the mean of its divisors is an integer number (2042671096704).

Almost surely, 2^{21001212212001} is an apocalyptic number.

21001212212001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21001212212001 is a deficient number, since it is larger than the sum of its proper divisors (11681525335263).

21001212212001 is a wasteful number, since it uses less digits than its factorization.

21001212212001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21277823980.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21001212212001 its reverse (10021221210012), we get a palindrome (31022433422013).

The spelling of 21001212212001 in words is "twenty-one trillion, one billion, two hundred twelve million, two hundred twelve thousand, one".