21928129989 has 4 divisors (see below), whose sum is σ = 29237506656. Its totient is φ = 14618753324.

The previous prime is 21928129981. The next prime is 21928129997. The reversal of 21928129989 is 98992182912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21928129981) and next prime (21928129997).

It is a cyclic number.

It is not a de Polignac number, because 21928129989 - 2³ = 21928129981 is a prime.

It is a super-2 number, since 2×21928129989² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21928129981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3654688329 + ... + 3654688334.

It is an arithmetic number, because the mean of its divisors is an integer number (7309376664).

Almost surely, 2^21928129989 is an apocalyptic number.

It is an amenable number.

21928129989 is a deficient number, since it is larger than the sum of its proper divisors (7309376667).

21928129989 is an equidigital number, since it uses as much as digits as its factorization.

21928129989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7309376666.

The product of its digits is 3359232, while the sum is 60.

The spelling of 21928129989 in words is "twenty-one billion, nine hundred twenty-eight million, one hundred twenty-nine thousand, nine hundred eighty-nine".