20721158429 has 4 divisors (see below), whose sum is σ = 20782645884. Its totient is φ = 20659670976.

The previous prime is 20721158399. The next prime is 20721158461. The reversal of 20721158429 is 92485112702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6961399225 + 13759759204 = 83435^2 + 117302^2 .

It is a cyclic number.

It is not a de Polignac number, because 20721158429 - 2¹⁶ = 20721092893 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721158489) 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, 30743222 + ... + 30743895.

It is an arithmetic number, because the mean of its divisors is an integer number (5195661471).

Almost surely, 2^20721158429 is an apocalyptic number.

It is an amenable number.

20721158429 is a deficient number, since it is larger than the sum of its proper divisors (61487455).

20721158429 is an equidigital number, since it uses as much as digits as its factorization.

20721158429 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61487454.

The product of its (nonzero) digits is 80640, while the sum is 41.

The spelling of 20721158429 in words is "twenty billion, seven hundred twenty-one million, one hundred fifty-eight thousand, four hundred twenty-nine".