78431501 has 2 divisors, whose sum is σ = 78431502. Its totient is φ = 78431500.

The previous prime is 78431447. The next prime is 78431503. The reversal of 78431501 is 10513487.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41538025 + 36893476 = 6445^2 + 6074^2 .

It is an emirp because it is prime and its reverse (10513487) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78431501 is a prime.

It is a super-2 number, since 2×78431501² = 12303000698226002, which contains 22 as substring.

Together with 78431503, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78431503) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39215750 + 39215751.

It is an arithmetic number, because the mean of its divisors is an integer number (39215751).

Almost surely, 2^78431501 is an apocalyptic number.

It is an amenable number.

78431501 is a deficient number, since it is larger than the sum of its proper divisors (1).

78431501 is an equidigital number, since it uses as much as digits as its factorization.

78431501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 78431501 is about 8856.1561074769. The cubic root of 78431501 is about 428.0523071280.

Adding to 78431501 its reverse (10513487), we get a palindrome (88944988).

The spelling of 78431501 in words is "seventy-eight million, four hundred thirty-one thousand, five hundred one".