21001167801 has 6 divisors (see below), whose sum is σ = 30335020170. Its totient is φ = 14000778528.

The previous prime is 21001167791. The next prime is 21001167809. The reversal of 21001167801 is 10876110012.

It can be written as a sum of positive squares in only one way, i.e., 12733994025 + 8267173776 = 112845^2 + 90924^2 .

It is not a de Polignac number, because 21001167801 - 2⁵ = 21001167769 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21001167809) 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, 1166731536 + ... + 1166731553.

It is an arithmetic number, because the mean of its divisors is an integer number (5055836695).

Almost surely, 2^21001167801 is an apocalyptic number.

It is an amenable number.

21001167801 is a deficient number, since it is larger than the sum of its proper divisors (9333852369).

21001167801 is a wasteful number, since it uses less digits than its factorization.

21001167801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2333463095 (or 2333463092 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 27.

Adding to 21001167801 its reverse (10876110012), we get a palindrome (31877277813).

The spelling of 21001167801 in words is "twenty-one billion, one million, one hundred sixty-seven thousand, eight hundred one".