78757421 has 2 divisors, whose sum is σ = 78757422. Its totient is φ = 78757420.

The previous prime is 78757411. The next prime is 78757429. The reversal of 78757421 is 12475787.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78517321 + 240100 = 8861^2 + 490^2 .

It is a cyclic number.

It is not a de Polignac number, because 78757421 - 2¹⁴ = 78741037 is a prime.

It is a super-3 number, since 3×78757421³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78757429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39378710 + 39378711.

It is an arithmetic number, because the mean of its divisors is an integer number (39378711).

Almost surely, 2^78757421 is an apocalyptic number.

It is an amenable number.

78757421 is a deficient number, since it is larger than the sum of its proper divisors (1).

78757421 is an equidigital number, since it uses as much as digits as its factorization.

78757421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 109760, while the sum is 41.

The square root of 78757421 is about 8874.5377907810. The cubic root of 78757421 is about 428.6444076938.

The spelling of 78757421 in words is "seventy-eight million, seven hundred fifty-seven thousand, four hundred twenty-one".