21166645248 has 672 divisors, whose sum is σ = 76331673600. Its totient is φ = 5852528640.

The previous prime is 21166645169. The next prime is 21166645249. The reversal of 21166645248 is 84254666112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (672).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21166645249) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 682794993 + ... + 682795023.

It is an arithmetic number, because the mean of its divisors is an integer number (113588800).

Almost surely, 2^21166645248 is an apocalyptic number.

21166645248 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21166645248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38165836800).

21166645248 is an abundant number, since it is smaller than the sum of its proper divisors (55165028352).

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

21166645248 is an frugal number, since it uses more digits than its factorization.

21166645248 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93 (or 43 counting only the distinct ones).

The product of its digits is 552960, while the sum is 45.

The spelling of 21166645248 in words is "twenty-one billion, one hundred sixty-six million, six hundred forty-five thousand, two hundred forty-eight".