21101853864 has 64 divisors (see below), whose sum is σ = 64928787840. Its totient is φ = 5565323520.

The previous prime is 21101853859. The next prime is 21101853893. The reversal of 21101853864 is 46835810112.

It is a super-2 number, since 2×21101853864² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4828827 + ... + 4833194.

It is an arithmetic number, because the mean of its divisors is an integer number (1014512310).

Almost surely, 2^21101853864 is an apocalyptic number.

21101853864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21101853864 is an abundant number, since it is smaller than the sum of its proper divisors (43826933976).

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

21101853864 is a wasteful number, since it uses less digits than its factorization.

21101853864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9662050 (or 9662046 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 39.

The spelling of 21101853864 in words is "twenty-one billion, one hundred one million, eight hundred fifty-three thousand, eight hundred sixty-four".