21365111971 has 16 divisors (see below), whose sum is σ = 25372569600. Its totient is φ = 17602145568.

The previous prime is 21365111969. The next prime is 21365112007. The reversal of 21365111971 is 17911156312.

It is not a de Polignac number, because 21365111971 - 2¹ = 21365111969 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21365111971.

It is not an unprimeable number, because it can be changed into a prime (21365111941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 190711 + ... + 281248.

It is an arithmetic number, because the mean of its divisors is an integer number (1585785600).

Almost surely, 2^21365111971 is an apocalyptic number.

21365111971 is a deficient number, since it is larger than the sum of its proper divisors (4007457629).

21365111971 is a wasteful number, since it uses less digits than its factorization.

21365111971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 472218.

The product of its digits is 11340, while the sum is 37.

The spelling of 21365111971 in words is "twenty-one billion, three hundred sixty-five million, one hundred eleven thousand, nine hundred seventy-one".