77644421 has 2 divisors, whose sum is σ = 77644422. Its totient is φ = 77644420.

The previous prime is 77644409. The next prime is 77644459. The reversal of 77644421 is 12444677.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39513796 + 38130625 = 6286^2 + 6175^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77644421 is a prime.

It is a super-2 number, since 2×77644421² = 12057312224850482, which contains 22 as substring.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77644921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38822210 + 38822211.

It is an arithmetic number, because the mean of its divisors is an integer number (38822211).

Almost surely, 2^77644421 is an apocalyptic number.

It is an amenable number.

77644421 is a deficient number, since it is larger than the sum of its proper divisors (1).

77644421 is an equidigital number, since it uses as much as digits as its factorization.

77644421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 37632, while the sum is 35.

The square root of 77644421 is about 8811.6071746305. The cubic root of 77644421 is about 426.6156193676.

The spelling of 77644421 in words is "seventy-seven million, six hundred forty-four thousand, four hundred twenty-one".