21007599991 has 8 divisors (see below), whose sum is σ = 24567027584. Its totient is φ = 17587757880.

The previous prime is 21007599959. The next prime is 21007599997. The reversal of 21007599991 is 19999570012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21007599991 - 2⁵ = 21007599959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21007599997) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 34896045 + ... + 34896646.

It is an arithmetic number, because the mean of its divisors is an integer number (3070878448).

Almost surely, 2^21007599991 is an apocalyptic number.

21007599991 is a deficient number, since it is larger than the sum of its proper divisors (3559427593).

21007599991 is an equidigital number, since it uses as much as digits as its factorization.

21007599991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69792741.

The product of its (nonzero) digits is 459270, while the sum is 52.

The spelling of 21007599991 in words is "twenty-one billion, seven million, five hundred ninety-nine thousand, nine hundred ninety-one".