21731064577 has 2 divisors, whose sum is σ = 21731064578. Its totient is φ = 21731064576.

The previous prime is 21731064529. The next prime is 21731064613. The reversal of 21731064577 is 77546013712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21694049521 + 37015056 = 147289^2 + 6084^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21731064577 is a prime.

It is not a weakly prime, because it can be changed into another prime (21731064517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865532288 + 10865532289.

It is an arithmetic number, because the mean of its divisors is an integer number (10865532289).

Almost surely, 2^21731064577 is an apocalyptic number.

It is an amenable number.

21731064577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21731064577 is an equidigital number, since it uses as much as digits as its factorization.

21731064577 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 246960, while the sum is 43.

The spelling of 21731064577 in words is "twenty-one billion, seven hundred thirty-one million, sixty-four thousand, five hundred seventy-seven".