77821243 has 2 divisors, whose sum is σ = 77821244. Its totient is φ = 77821242.

The previous prime is 77821229. The next prime is 77821273. The reversal of 77821243 is 34212877.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 77821243 - 2²¹ = 75724091 is a prime.

It is a super-2 number, since 2×77821243² = 12112291724130098, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 77821199 and 77821208.

It is not a weakly prime, because it can be changed into another prime (77821273) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38910621 + 38910622.

It is an arithmetic number, because the mean of its divisors is an integer number (38910622).

Almost surely, 2^77821243 is an apocalyptic number.

77821243 is a deficient number, since it is larger than the sum of its proper divisors (1).

77821243 is an equidigital number, since it uses as much as digits as its factorization.

77821243 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18816, while the sum is 34.

The square root of 77821243 is about 8821.6349391709. The cubic root of 77821243 is about 426.9392220807.

It can be divided in two parts, 7782 and 1243, that added together give a square (9025 = 95²).

The spelling of 77821243 in words is "seventy-seven million, eight hundred twenty-one thousand, two hundred forty-three".