28941691663721 has 2 divisors, whose sum is σ = 28941691663722. Its totient is φ = 28941691663720.

The previous prime is 28941691663697. The next prime is 28941691663813. The reversal of 28941691663721 is 12736619614982.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17514317070121 + 11427374593600 = 4185011^2 + 3380440^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28941691663721 is a prime.

It is not a weakly prime, because it can be changed into another prime (28941691663921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14470845831860 + 14470845831861.

It is an arithmetic number, because the mean of its divisors is an integer number (14470845831861).

Almost surely, 2^{28941691663721} is an apocalyptic number.

It is an amenable number.

28941691663721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28941691663721 is an equidigital number, since it uses as much as digits as its factorization.

28941691663721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47029248, while the sum is 65.

The spelling of 28941691663721 in words is "twenty-eight trillion, nine hundred forty-one billion, six hundred ninety-one million, six hundred sixty-three thousand, seven hundred twenty-one".