21001000001201 has 6 divisors (see below), whose sum is σ = 23083743803106. Its totient is φ = 19091818182800.

The previous prime is 21001000001197. The next prime is 21001000001209. The reversal of 21001000001201 is 10210000010012.

It can be written as a sum of positive squares in only one way, i.e., 18856090369600 + 2144909631601 = 4342360^2 + 1464551^2 .

It is not a de Polignac number, because 21001000001201 - 2² = 21001000001197 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001000001209) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 86780991620 + ... + 86780991861.

It is an arithmetic number, because the mean of its divisors is an integer number (3847290633851).

Almost surely, 2^{21001000001201} is an apocalyptic number.

It is an amenable number.

21001000001201 is a deficient number, since it is larger than the sum of its proper divisors (2082743801905).

21001000001201 is a wasteful number, since it uses less digits than its factorization.

21001000001201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173561983503 (or 173561983492 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21001000001201 its reverse (10210000010012), we get a palindrome (31211000011213).

The spelling of 21001000001201 in words is "twenty-one trillion, one billion, one thousand, two hundred one".