21957370117 has 2 divisors, whose sum is σ = 21957370118. Its totient is φ = 21957370116.

The previous prime is 21957370109. The next prime is 21957370129. The reversal of 21957370117 is 71107375912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18866121316 + 3091248801 = 137354^2 + 55599^2 .

It is a cyclic number.

It is not a de Polignac number, because 21957370117 - 2³ = 21957370109 is a prime.

It is a super-2 number, since 2×21957370117² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21957370217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978685058 + 10978685059.

It is an arithmetic number, because the mean of its divisors is an integer number (10978685059).

Almost surely, 2^21957370117 is an apocalyptic number.

It is an amenable number.

21957370117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21957370117 is an equidigital number, since it uses as much as digits as its factorization.

21957370117 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 92610, while the sum is 43.

The spelling of 21957370117 in words is "twenty-one billion, nine hundred fifty-seven million, three hundred seventy thousand, one hundred seventeen".