21207743971 has 8 divisors (see below), whose sum is σ = 21254220000. Its totient is φ = 21161317632.

The previous prime is 21207743917. The next prime is 21207744013. The reversal of 21207743971 is 17934770212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21207743971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21207743911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 916581 + ... + 939433.

It is an arithmetic number, because the mean of its divisors is an integer number (2656777500).

Almost surely, 2^21207743971 is an apocalyptic number.

21207743971 is a deficient number, since it is larger than the sum of its proper divisors (46476029).

21207743971 is a wasteful number, since it uses less digits than its factorization.

21207743971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24845.

The product of its (nonzero) digits is 148176, while the sum is 43.

The spelling of 21207743971 in words is "twenty-one billion, two hundred seven million, seven hundred forty-three thousand, nine hundred seventy-one".