77821001 has 2 divisors, whose sum is σ = 77821002. Its totient is φ = 77821000.

The previous prime is 77820997. The next prime is 77821031. The reversal of 77821001 is 10012877.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55115776 + 22705225 = 7424^2 + 4765^2 .

It is a cyclic number.

It is not a de Polignac number, because 77821001 - 2² = 77820997 is a prime.

It is a super-2 number, since 2×77821001² = 12112216393284002, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (77821031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38910500 + 38910501.

It is an arithmetic number, because the mean of its divisors is an integer number (38910501).

Almost surely, 2^77821001 is an apocalyptic number.

It is an amenable number.

77821001 is a deficient number, since it is larger than the sum of its proper divisors (1).

77821001 is an equidigital number, since it uses as much as digits as its factorization.

77821001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 77821001 is about 8821.6212228819. The cubic root of 77821001 is about 426.9387795306.

Adding to 77821001 its reverse (10012877), we get a palindrome (87833878).

The spelling of 77821001 in words is "seventy-seven million, eight hundred twenty-one thousand, one".