21505171933 has 16 divisors (see below), whose sum is σ = 25096055040. Its totient is φ = 18045495936.

The previous prime is 21505171927. The next prime is 21505171967. The reversal of 21505171933 is 33917150512.

It is a cyclic number.

It is not a de Polignac number, because 21505171933 - 2¹⁷ = 21505040861 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21505171892 and 21505171901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21505171133) 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, 106128 + ... + 232966.

It is an arithmetic number, because the mean of its divisors is an integer number (1568503440).

Almost surely, 2^21505171933 is an apocalyptic number.

It is an amenable number.

21505171933 is a deficient number, since it is larger than the sum of its proper divisors (3590883107).

21505171933 is a wasteful number, since it uses less digits than its factorization.

21505171933 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127356.

The product of its (nonzero) digits is 28350, while the sum is 37.

The spelling of 21505171933 in words is "twenty-one billion, five hundred five million, one hundred seventy-one thousand, nine hundred thirty-three".