21012121659 has 8 divisors (see below), whose sum is σ = 28399945552. Its totient is φ = 13816189440.

The previous prime is 21012121631. The next prime is 21012121673. The reversal of 21012121659 is 95612121012.

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

It is not a de Polignac number, because 21012121659 - 2²⁴ = 20995344443 is a prime.

It is a super-2 number, since 2×21012121659² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012121609) 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, 47972662 + ... + 47973099.

It is an arithmetic number, because the mean of its divisors is an integer number (3549993194).

Almost surely, 2^21012121659 is an apocalyptic number.

21012121659 is a deficient number, since it is larger than the sum of its proper divisors (7387823893).

21012121659 is an equidigital number, since it uses as much as digits as its factorization.

21012121659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95945837.

The product of its (nonzero) digits is 2160, while the sum is 30.

The spelling of 21012121659 in words is "twenty-one billion, twelve million, one hundred twenty-one thousand, six hundred fifty-nine".