78121697 has 2 divisors, whose sum is σ = 78121698. Its totient is φ = 78121696.

The previous prime is 78121657. The next prime is 78121709. The reversal of 78121697 is 79612187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49434961 + 28686736 = 7031^2 + 5356^2 .

It is a cyclic number.

It is not a de Polignac number, because 78121697 - 2¹⁸ = 77859553 is a prime.

It is a super-2 number, since 2×78121697² = 12205999084319618, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78121657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39060848 + 39060849.

It is an arithmetic number, because the mean of its divisors is an integer number (39060849).

Almost surely, 2^78121697 is an apocalyptic number.

It is an amenable number.

78121697 is a deficient number, since it is larger than the sum of its proper divisors (1).

78121697 is an equidigital number, since it uses as much as digits as its factorization.

78121697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42336, while the sum is 41.

The square root of 78121697 is about 8838.6479169611. The cubic root of 78121697 is about 427.4879619970.

The spelling of 78121697 in words is "seventy-eight million, one hundred twenty-one thousand, six hundred ninety-seven".