74781821 has 2 divisors, whose sum is σ = 74781822. Its totient is φ = 74781820.

The previous prime is 74781799. The next prime is 74781869. The reversal of 74781821 is 12818747.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74736025 + 45796 = 8645^2 + 214^2 .

It is an emirp because it is prime and its reverse (12818747) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 74781821 - 2⁶ = 74781757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (74781871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37390910 + 37390911.

It is an arithmetic number, because the mean of its divisors is an integer number (37390911).

Almost surely, 2^74781821 is an apocalyptic number.

It is an amenable number.

74781821 is a deficient number, since it is larger than the sum of its proper divisors (1).

74781821 is an equidigital number, since it uses as much as digits as its factorization.

74781821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25088, while the sum is 38.

The square root of 74781821 is about 8647.6482930332. The cubic root of 74781821 is about 421.3070037063.

The spelling of 74781821 in words is "seventy-four million, seven hundred eighty-one thousand, eight hundred twenty-one".