97138781 has 2 divisors, whose sum is σ = 97138782. Its totient is φ = 97138780.

The previous prime is 97138759. The next prime is 97138813. The reversal of 97138781 is 18783179.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 97022500 + 116281 = 9850^2 + 341^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-97138781 is a prime.

It is a super-2 number, since 2×97138781² = 18871885548331922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (97138751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 48569390 + 48569391.

It is an arithmetic number, because the mean of its divisors is an integer number (48569391).

Almost surely, 2^97138781 is an apocalyptic number.

It is an amenable number.

97138781 is a deficient number, since it is larger than the sum of its proper divisors (1).

97138781 is an equidigital number, since it uses as much as digits as its factorization.

97138781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 44.

The square root of 97138781 is about 9855.9008213354. The cubic root of 97138781 is about 459.6891109803.

The spelling of 97138781 in words is "ninety-seven million, one hundred thirty-eight thousand, seven hundred eighty-one".