97816781 has 4 divisors (see below), whose sum is σ = 97841532. Its totient is φ = 97792032.

The previous prime is 97816757. The next prime is 97816799. The reversal of 97816781 is 18761879.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13801225 + 84015556 = 3715^2 + 9166^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-97816781 is a prime.

It is a super-2 number, since 2×97816781² = 19136245290403922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (97816721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4970 + ... + 14843.

It is an arithmetic number, because the mean of its divisors is an integer number (24460383).

Almost surely, 2^97816781 is an apocalyptic number.

It is an amenable number.

97816781 is a deficient number, since it is larger than the sum of its proper divisors (24751).

97816781 is a wasteful number, since it uses less digits than its factorization.

97816781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24750.

The product of its digits is 169344, while the sum is 47.

The square root of 97816781 is about 9890.2366503537. The cubic root of 97816781 is about 460.7561303968.

The spelling of 97816781 in words is "ninety-seven million, eight hundred sixteen thousand, seven hundred eighty-one".