91356530079721 has 9 divisors (see below), whose sum is σ = 93342101541181. Its totient is φ = 89412334449772.

The previous prime is 91356530079677. The next prime is 91356530079761. The reversal of 91356530079721 is 12797003565319.

The square root of 91356530079721 is 9558061.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 91356530079721 - 2⁹ = 91356530079209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91356530079761) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 449127186 + ... + 449330548.

Almost surely, 2^{91356530079721} is an apocalyptic number.

91356530079721 is the 9558061-st square number.

91356530079721 is the 4779031-st centered octagonal number.

It is an amenable number.

91356530079721 is a deficient number, since it is larger than the sum of its proper divisors (1985571461460).

91356530079721 is an frugal number, since it uses more digits than its factorization.

91356530079721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406820 (or 203410 counting only the distinct ones).

The product of its (nonzero) digits is 10716300, while the sum is 58.

The spelling of 91356530079721 in words is "ninety-one trillion, three hundred fifty-six billion, five hundred thirty million, seventy-nine thousand, seven hundred twenty-one".