21611789357 has 4 divisors (see below), whose sum is σ = 21907841340. Its totient is φ = 21315737376.

The previous prime is 21611789351. The next prime is 21611789363. The reversal of 21611789357 is 75398711612.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (21611789351) and next prime (21611789363).

It can be written as a sum of positive squares in 2 ways, for example, as 8945187241 + 12666602116 = 94579^2 + 112546^2 .

It is a cyclic number.

It is not a de Polignac number, because 21611789357 - 2⁴ = 21611789341 is a prime.

It is a super-2 number, since 2×21611789357² (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 (21611789351) 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, 148025882 + ... + 148026027.

It is an arithmetic number, because the mean of its divisors is an integer number (5476960335).

Almost surely, 2^21611789357 is an apocalyptic number.

It is an amenable number.

21611789357 is a deficient number, since it is larger than the sum of its proper divisors (296051983).

21611789357 is an equidigital number, since it uses as much as digits as its factorization.

21611789357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296051982.

The product of its digits is 635040, while the sum is 50.

The spelling of 21611789357 in words is "twenty-one billion, six hundred eleven million, seven hundred eighty-nine thousand, three hundred fifty-seven".