76421721821 has 2 divisors, whose sum is σ = 76421721822. Its totient is φ = 76421721820.

The previous prime is 76421721781. The next prime is 76421721829. The reversal of 76421721821 is 12812712467.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71938749796 + 4482972025 = 268214^2 + 66955^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-76421721821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (76421721829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38210860910 + 38210860911.

It is an arithmetic number, because the mean of its divisors is an integer number (38210860911).

Almost surely, 2^76421721821 is an apocalyptic number.

It is an amenable number.

76421721821 is a deficient number, since it is larger than the sum of its proper divisors (1).

76421721821 is an equidigital number, since it uses as much as digits as its factorization.

76421721821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75264, while the sum is 41.

The spelling of 76421721821 in words is "seventy-six billion, four hundred twenty-one million, seven hundred twenty-one thousand, eight hundred twenty-one".