21108891507 has 8 divisors (see below), whose sum is σ = 30703842240. Its totient is φ = 12793267560.

The previous prime is 21108891499. The next prime is 21108891527. The reversal of 21108891507 is 70519880112.

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

It is not a de Polignac number, because 21108891507 - 2³ = 21108891499 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21108891527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 319831657 + ... + 319831722.

It is an arithmetic number, because the mean of its divisors is an integer number (3837980280).

Almost surely, 2^21108891507 is an apocalyptic number.

21108891507 is a deficient number, since it is larger than the sum of its proper divisors (9594950733).

21108891507 is a wasteful number, since it uses less digits than its factorization.

21108891507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639663393.

The product of its (nonzero) digits is 40320, while the sum is 42.

The spelling of 21108891507 in words is "twenty-one billion, one hundred eight million, eight hundred ninety-one thousand, five hundred seven".