21029228921 has 4 divisors (see below), whose sum is σ = 21033481344. Its totient is φ = 21024976500.

The previous prime is 21029228911. The next prime is 21029228929. The reversal of 21029228921 is 12982292012.

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 a cyclic number.

It is not a de Polignac number, because 21029228921 - 2¹⁴ = 21029212537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21029228929) 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 3 ways as a sum of consecutive naturals, for example, 2118785 + ... + 2128686.

It is an arithmetic number, because the mean of its divisors is an integer number (5258370336).

Almost surely, 2^21029228921 is an apocalyptic number.

It is an amenable number.

21029228921 is a deficient number, since it is larger than the sum of its proper divisors (4252423).

21029228921 is an equidigital number, since it uses as much as digits as its factorization.

21029228921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4252422.

The product of its (nonzero) digits is 20736, while the sum is 38.

The spelling of 21029228921 in words is "twenty-one billion, twenty-nine million, two hundred twenty-eight thousand, nine hundred twenty-one".