21405872563 has 16 divisors (see below), whose sum is σ = 21860349472. Its totient is φ = 20956320000.

The previous prime is 21405872561. The next prime is 21405872629. The reversal of 21405872563 is 36527850412.

It is a cyclic number.

It is not a de Polignac number, because 21405872563 - 2¹ = 21405872561 is a prime.

It is a super-3 number, since 3×21405872563³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21405872561) 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, 6483013 + ... + 6486313.

It is an arithmetic number, because the mean of its divisors is an integer number (1366271842).

Almost surely, 2^21405872563 is an apocalyptic number.

21405872563 is a deficient number, since it is larger than the sum of its proper divisors (454476909).

21405872563 is a wasteful number, since it uses less digits than its factorization.

21405872563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4006.

The product of its (nonzero) digits is 403200, while the sum is 43.

The spelling of 21405872563 in words is "twenty-one billion, four hundred five million, eight hundred seventy-two thousand, five hundred sixty-three".