77720381 has 4 divisors (see below), whose sum is σ = 81099552. Its totient is φ = 74341212.

The previous prime is 77720369. The next prime is 77720411. The reversal of 77720381 is 18302777.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 77720381 - 2¹⁰ = 77719357 is a prime.

It is a super-2 number, since 2×77720381² = 12080915245570322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77720351) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1689551 + ... + 1689596.

It is an arithmetic number, because the mean of its divisors is an integer number (20274888).

Almost surely, 2^77720381 is an apocalyptic number.

It is an amenable number.

77720381 is a deficient number, since it is larger than the sum of its proper divisors (3379171).

77720381 is a wasteful number, since it uses less digits than its factorization.

77720381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3379170.

The product of its (nonzero) digits is 16464, while the sum is 35.

The square root of 77720381 is about 8815.9163448844. The cubic root of 77720381 is about 426.7546942262.

The spelling of 77720381 in words is "seventy-seven million, seven hundred twenty thousand, three hundred eighty-one".