21006638609575 has 24 divisors (see below), whose sum is σ = 26282157834240. Its totient is φ = 16654681461600.

The previous prime is 21006638609521. The next prime is 21006638609609. The reversal of 21006638609575 is 57590683660012.

It is a de Polignac number, because none of the positive numbers 2^k-21006638609575 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 738895 + ... + 6523744.

It is an arithmetic number, because the mean of its divisors is an integer number (1095089909760).

Almost surely, 2^{21006638609575} is an apocalyptic number.

21006638609575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21006638609575 is a deficient number, since it is larger than the sum of its proper divisors (5275519224665).

21006638609575 is a wasteful number, since it uses less digits than its factorization.

21006638609575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7263687 (or 7263682 counting only the distinct ones).

The product of its (nonzero) digits is 16329600, while the sum is 58.

The spelling of 21006638609575 in words is "twenty-one trillion, six billion, six hundred thirty-eight million, six hundred nine thousand, five hundred seventy-five".