20729961421 has 8 divisors (see below), whose sum is σ = 22422064280. Its totient is φ = 19051785792.

The previous prime is 20729961389. The next prime is 20729961451. The reversal of 20729961421 is 12416992702.

It can be written as a sum of positive squares in 4 ways, for example, as 10938858921 + 9791102500 = 104589^2 + 98950^2 .

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

It is not a de Polignac number, because 20729961421 - 2⁵ = 20729961389 is a prime.

It is a super-2 number, since 2×20729961421² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20729961451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3478710 + ... + 3484663.

It is an arithmetic number, because the mean of its divisors is an integer number (2802758035).

Almost surely, 2^20729961421 is an apocalyptic number.

It is an amenable number.

20729961421 is a deficient number, since it is larger than the sum of its proper divisors (1692102859).

20729961421 is a wasteful number, since it uses less digits than its factorization.

20729961421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6963615.

The product of its (nonzero) digits is 108864, while the sum is 43.

The spelling of 20729961421 in words is "twenty billion, seven hundred twenty-nine million, nine hundred sixty-one thousand, four hundred twenty-one".