78374583821 has 2 divisors, whose sum is σ = 78374583822. Its totient is φ = 78374583820.

The previous prime is 78374583803. The next prime is 78374583851. The reversal of 78374583821 is 12838547387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48103455625 + 30271128196 = 219325^2 + 173986^2 .

It is a cyclic number.

It is not a de Polignac number, because 78374583821 - 2¹⁸ = 78374321677 is a prime.

It is a super-2 number, since 2×78374583821² (a number of 23 digits) 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 (78374583851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39187291910 + 39187291911.

It is an arithmetic number, because the mean of its divisors is an integer number (39187291911).

Almost surely, 2^78374583821 is an apocalyptic number.

It is an amenable number.

78374583821 is a deficient number, since it is larger than the sum of its proper divisors (1).

78374583821 is an equidigital number, since it uses as much as digits as its factorization.

78374583821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9031680, while the sum is 56.

The spelling of 78374583821 in words is "seventy-eight billion, three hundred seventy-four million, five hundred eighty-three thousand, eight hundred twenty-one".