21971061937018 has 4 divisors (see below), whose sum is σ = 32956592905530. Its totient is φ = 10985530968508.

The previous prime is 21971061937001. The next prime is 21971061937087. The reversal of 21971061937018 is 81073916017912.

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

It can be written as a sum of positive squares in only one way, i.e., 17242816087809 + 4728245849209 = 4152447^2 + 2174453^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21971061937018.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5492765484253 + ... + 5492765484256.

Almost surely, 2^{21971061937018} is an apocalyptic number.

21971061937018 is a deficient number, since it is larger than the sum of its proper divisors (10985530968512).

21971061937018 is a wasteful number, since it uses less digits than its factorization.

21971061937018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10985530968511.

The product of its (nonzero) digits is 1143072, while the sum is 55.

The spelling of 21971061937018 in words is "twenty-one trillion, nine hundred seventy-one billion, sixty-one million, nine hundred thirty-seven thousand, eighteen".