81201761 has 2 divisors, whose sum is σ = 81201762. Its totient is φ = 81201760.

The previous prime is 81201733. The next prime is 81201767. The reversal of 81201761 is 16710218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59290000 + 21911761 = 7700^2 + 4681^2 .

It is a cyclic number.

It is not a de Polignac number, because 81201761 - 2⁶ = 81201697 is a prime.

It is a super-2 number, since 2×81201761² = 13187451979002242, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81201761.

It is not a weakly prime, because it can be changed into another prime (81201767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40600880 + 40600881.

It is an arithmetic number, because the mean of its divisors is an integer number (40600881).

Almost surely, 2^81201761 is an apocalyptic number.

It is an amenable number.

81201761 is a deficient number, since it is larger than the sum of its proper divisors (1).

81201761 is an equidigital number, since it uses as much as digits as its factorization.

81201761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 81201761 is about 9011.2019730999. The cubic root of 81201761 is about 433.0338197871.

Adding to 81201761 its reverse (16710218), we get a palindrome (97911979).

The spelling of 81201761 in words is "eighty-one million, two hundred one thousand, seven hundred sixty-one".