21505168201 has 16 divisors (see below), whose sum is σ = 24146668800. Its totient is φ = 18986198400.

The previous prime is 21505168169. The next prime is 21505168219. The reversal of 21505168201 is 10286150512.

It is a cyclic number.

It is not a de Polignac number, because 21505168201 - 2⁵ = 21505168169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21505168241) 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, 149836 + ... + 255853.

It is an arithmetic number, because the mean of its divisors is an integer number (1509166800).

Almost surely, 2^21505168201 is an apocalyptic number.

It is an amenable number.

21505168201 is a deficient number, since it is larger than the sum of its proper divisors (2641500599).

21505168201 is a wasteful number, since it uses less digits than its factorization.

21505168201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405840.

The product of its (nonzero) digits is 4800, while the sum is 31.

The spelling of 21505168201 in words is "twenty-one billion, five hundred five million, one hundred sixty-eight thousand, two hundred one".