21017148975 has 72 divisors (see below), whose sum is σ = 40384758960. Its totient is φ = 10822533120.

The previous prime is 21017148973. The next prime is 21017148979. The reversal of 21017148975 is 57984171012.

It is a happy number.

It is not a de Polignac number, because 21017148975 - 2¹ = 21017148973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21017148975.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21017148973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 116527 + ... + 235823.

It is an arithmetic number, because the mean of its divisors is an integer number (560899430).

Almost surely, 2^21017148975 is an apocalyptic number.

21017148975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21017148975 is a deficient number, since it is larger than the sum of its proper divisors (19367609985).

21017148975 is a wasteful number, since it uses less digits than its factorization.

21017148975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119351 (or 119334 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 45.

The spelling of 21017148975 in words is "twenty-one billion, seventeen million, one hundred forty-eight thousand, nine hundred seventy-five".