21506777215619 has 2 divisors, whose sum is σ = 21506777215620. Its totient is φ = 21506777215618.

The previous prime is 21506777215529. The next prime is 21506777215631. The reversal of 21506777215619 is 91651277760512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21506777215619 - 2²⁰ = 21506776167043 is a prime.

It is a super-2 number, since 2×21506777215619² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21506777215639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753388607809 + 10753388607810.

It is an arithmetic number, because the mean of its divisors is an integer number (10753388607810).

Almost surely, 2^{21506777215619} is an apocalyptic number.

21506777215619 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506777215619 is an equidigital number, since it uses as much as digits as its factorization.

21506777215619 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11113200, while the sum is 59.

The spelling of 21506777215619 in words is "twenty-one trillion, five hundred six billion, seven hundred seventy-seven million, two hundred fifteen thousand, six hundred nineteen".