78408001347521 has 2 divisors, whose sum is σ = 78408001347522. Its totient is φ = 78408001347520.

The previous prime is 78408001347517. The next prime is 78408001347553. The reversal of 78408001347521 is 12574310080487.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74382621215296 + 4025380132225 = 8624536^2 + 2006335^2 .

It is a cyclic number.

It is not a de Polignac number, because 78408001347521 - 2² = 78408001347517 is a prime.

It is a super-2 number, since 2×78408001347521² (a number of 29 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 78408001347521.

It is not a weakly prime, because it can be changed into another prime (78408001343521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39204000673760 + 39204000673761.

It is an arithmetic number, because the mean of its divisors is an integer number (39204000673761).

Almost surely, 2^{78408001347521} is an apocalyptic number.

It is an amenable number.

78408001347521 is a deficient number, since it is larger than the sum of its proper divisors (1).

78408001347521 is an equidigital number, since it uses as much as digits as its factorization.

78408001347521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1505280, while the sum is 50.

The spelling of 78408001347521 in words is "seventy-eight trillion, four hundred eight billion, one million, three hundred forty-seven thousand, five hundred twenty-one".