21179887775957 has 2 divisors, whose sum is σ = 21179887775958. Its totient is φ = 21179887775956.

The previous prime is 21179887775947. The next prime is 21179887776011. The reversal of 21179887775957 is 75957778897112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18367404489841 + 2812483286116 = 4285721^2 + 1677046^2 .

It is a cyclic number.

It is not a de Polignac number, because 21179887775957 - 2⁴ = 21179887775941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21179887775927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10589943887978 + 10589943887979.

It is an arithmetic number, because the mean of its divisors is an integer number (10589943887979).

Almost surely, 2^{21179887775957} is an apocalyptic number.

It is an amenable number.

21179887775957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21179887775957 is an equidigital number, since it uses as much as digits as its factorization.

21179887775957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4356374400, while the sum is 83.

The spelling of 21179887775957 in words is "twenty-one trillion, one hundred seventy-nine billion, eight hundred eighty-seven million, seven hundred seventy-five thousand, nine hundred fifty-seven".