21201011999971 has 4 divisors (see below), whose sum is σ = 21694058790712. Its totient is φ = 20707965209232.

The previous prime is 21201011999969. The next prime is 21201012000011. The reversal of 21201011999971 is 17999911010212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21201011999971 - 2¹ = 21201011999969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201011999471) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 246523395306 + ... + 246523395391.

It is an arithmetic number, because the mean of its divisors is an integer number (5423514697678).

Almost surely, 2^{21201011999971} is an apocalyptic number.

21201011999971 is a deficient number, since it is larger than the sum of its proper divisors (493046790741).

21201011999971 is an equidigital number, since it uses as much as digits as its factorization.

21201011999971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 493046790740.

The product of its (nonzero) digits is 183708, while the sum is 52.

The spelling of 21201011999971 in words is "twenty-one trillion, two hundred one billion, eleven million, nine hundred ninety-nine thousand, nine hundred seventy-one".