21979254066 has 256 divisors, whose sum is σ = 60908101632. Its totient is φ = 5109350400.

The previous prime is 21979254013. The next prime is 21979254103. The reversal of 21979254066 is 66045297912.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 50760186 + ... + 50760618.

It is an arithmetic number, because the mean of its divisors is an integer number (237922272).

Almost surely, 2^21979254066 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21979254066, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30454050816).

21979254066 is an abundant number, since it is smaller than the sum of its proper divisors (38928847566).

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

21979254066 is a wasteful number, since it uses less digits than its factorization.

21979254066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 777.

The product of its (nonzero) digits is 1632960, while the sum is 51.

The spelling of 21979254066 in words is "twenty-one billion, nine hundred seventy-nine million, two hundred fifty-four thousand, sixty-six".