81701537 has 2 divisors, whose sum is σ = 81701538. Its totient is φ = 81701536.

The previous prime is 81701531. The next prime is 81701549. The reversal of 81701537 is 73510718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56310016 + 25391521 = 7504^2 + 5039^2 .

It is a cyclic number.

It is not a de Polignac number, because 81701537 - 2²⁰ = 80652961 is a prime.

It is a super-2 number, since 2×81701537² = 13350282296324738, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81701531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40850768 + 40850769.

It is an arithmetic number, because the mean of its divisors is an integer number (40850769).

Almost surely, 2^81701537 is an apocalyptic number.

It is an amenable number.

81701537 is a deficient number, since it is larger than the sum of its proper divisors (1).

81701537 is an equidigital number, since it uses as much as digits as its factorization.

81701537 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5880, while the sum is 32.

The square root of 81701537 is about 9038.8902526804. The cubic root of 81701537 is about 433.9204073711.

The spelling of 81701537 in words is "eighty-one million, seven hundred one thousand, five hundred thirty-seven".