81401777 has 2 divisors, whose sum is σ = 81401778. Its totient is φ = 81401776.

The previous prime is 81401759. The next prime is 81401783. The reversal of 81401777 is 77710418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56010256 + 25391521 = 7484^2 + 5039^2 .

It is a cyclic number.

It is not a de Polignac number, because 81401777 - 2²⁰ = 80353201 is a prime.

It is a Chen prime.

It is equal to p_4746563 and since 81401777 and 4746563 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81401707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40700888 + 40700889.

It is an arithmetic number, because the mean of its divisors is an integer number (40700889).

Almost surely, 2^81401777 is an apocalyptic number.

It is an amenable number.

81401777 is a deficient number, since it is larger than the sum of its proper divisors (1).

81401777 is an equidigital number, since it uses as much as digits as its factorization.

81401777 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10976, while the sum is 35.

The square root of 81401777 is about 9022.2933337373. The cubic root of 81401777 is about 433.3890775756.

The spelling of 81401777 in words is "eighty-one million, four hundred one thousand, seven hundred seventy-seven".