21291216029 has 4 divisors (see below), whose sum is σ = 21347393760. Its totient is φ = 21235038300.

The previous prime is 21291215929. The next prime is 21291216031. The reversal of 21291216029 is 92061219212.

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 21291216029 - 2⁸ = 21291215773 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21291216029.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21291210029) 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, 28088297 + ... + 28089054.

It is an arithmetic number, because the mean of its divisors is an integer number (5336848440).

Almost surely, 2^21291216029 is an apocalyptic number.

It is an amenable number.

21291216029 is a deficient number, since it is larger than the sum of its proper divisors (56177731).

21291216029 is an equidigital number, since it uses as much as digits as its factorization.

21291216029 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56177730.

The product of its (nonzero) digits is 7776, while the sum is 35.

The spelling of 21291216029 in words is "twenty-one billion, two hundred ninety-one million, two hundred sixteen thousand, twenty-nine".