21231750473777 has 2 divisors, whose sum is σ = 21231750473778. Its totient is φ = 21231750473776.

The previous prime is 21231750473737. The next prime is 21231750473789. The reversal of 21231750473777 is 77737405713212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21224163366961 + 7587106816 = 4606969^2 + 87104^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231750473777 - 2³⁴ = 21214570604593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21231750473737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615875236888 + 10615875236889.

It is an arithmetic number, because the mean of its divisors is an integer number (10615875236889).

Almost surely, 2^{21231750473777} is an apocalyptic number.

It is an amenable number.

21231750473777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231750473777 is an equidigital number, since it uses as much as digits as its factorization.

21231750473777 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12101040, while the sum is 56.

The spelling of 21231750473777 in words is "twenty-one trillion, two hundred thirty-one billion, seven hundred fifty million, four hundred seventy-three thousand, seven hundred seventy-seven".