21111615071 has 4 divisors (see below), whose sum is σ = 21792634944. Its totient is φ = 20430595200.

The previous prime is 21111615059. The next prime is 21111615079. The reversal of 21111615071 is 17051611112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111615071 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21111615071.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111615079) 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, 340509890 + ... + 340509951.

It is an arithmetic number, because the mean of its divisors is an integer number (5448158736).

Almost surely, 2^21111615071 is an apocalyptic number.

21111615071 is a deficient number, since it is larger than the sum of its proper divisors (681019873).

21111615071 is an equidigital number, since it uses as much as digits as its factorization.

21111615071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681019872.

The product of its (nonzero) digits is 420, while the sum is 26.

The spelling of 21111615071 in words is "twenty-one billion, one hundred eleven million, six hundred fifteen thousand, seventy-one".