21504643611 has 16 divisors (see below), whose sum is σ = 32288498688. Its totient is φ = 12612693600.

The previous prime is 21504643609. The next prime is 21504643649. The reversal of 21504643611 is 11634640512.

It is not a de Polignac number, because 21504643611 - 2¹ = 21504643609 is a prime.

It is a super-2 number, since 2×21504643611² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21504643411) 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, 10509556 + ... + 10511601.

It is an arithmetic number, because the mean of its divisors is an integer number (2018031168).

Almost surely, 2^21504643611 is an apocalyptic number.

21504643611 is a deficient number, since it is larger than the sum of its proper divisors (10783855077).

21504643611 is a wasteful number, since it uses less digits than its factorization.

21504643611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21021202.

The product of its (nonzero) digits is 17280, while the sum is 33.

The spelling of 21504643611 in words is "twenty-one billion, five hundred four million, six hundred forty-three thousand, six hundred eleven".