21154535621077 has 2 divisors, whose sum is σ = 21154535621078. Its totient is φ = 21154535621076.

The previous prime is 21154535620963. The next prime is 21154535621123. The reversal of 21154535621077 is 77012653545112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19501462274116 + 1653073346961 = 4416046^2 + 1285719^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154535621077 - 2¹⁹ = 21154535096789 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21154535621077.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21154535631077) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577267810538 + 10577267810539.

It is an arithmetic number, because the mean of its divisors is an integer number (10577267810539).

Almost surely, 2^{21154535621077} is an apocalyptic number.

It is an amenable number.

21154535621077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154535621077 is an equidigital number, since it uses as much as digits as its factorization.

21154535621077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1764000, while the sum is 49.

The spelling of 21154535621077 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred thirty-five million, six hundred twenty-one thousand, seventy-seven".