21168539064 has 24 divisors (see below), whose sum is σ = 57331460160. Its totient is φ = 7056179664.

The previous prime is 21168539057. The next prime is 21168539107. The reversal of 21168539064 is 46093586112.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21168539064² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 147003672 + ... + 147003815.

It is an arithmetic number, because the mean of its divisors is an integer number (2388810840).

Almost surely, 2^21168539064 is an apocalyptic number.

21168539064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21168539064 is an abundant number, since it is smaller than the sum of its proper divisors (36162921096).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21168539064 is a wasteful number, since it uses less digits than its factorization.

21168539064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294007499 (or 294007492 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The spelling of 21168539064 in words is "twenty-one billion, one hundred sixty-eight million, five hundred thirty-nine thousand, sixty-four".