77781091 has 4 divisors (see below), whose sum is σ = 78005592. Its totient is φ = 77556592.

The previous prime is 77781073. The next prime is 77781107. The reversal of 77781091 is 19018777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19018777 = 37 ⋅514021.

It is a cyclic number.

It is not a de Polignac number, because 77781091 - 2¹³ = 77772899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77781031) 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, 111730 + ... + 112423.

It is an arithmetic number, because the mean of its divisors is an integer number (19501398).

Almost surely, 2^77781091 is an apocalyptic number.

77781091 is a deficient number, since it is larger than the sum of its proper divisors (224501).

77781091 is a wasteful number, since it uses less digits than its factorization.

77781091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224500.

The product of its (nonzero) digits is 24696, while the sum is 40.

The square root of 77781091 is about 8819.3588769252. The cubic root of 77781091 is about 426.8657827812.

The spelling of 77781091 in words is "seventy-seven million, seven hundred eighty-one thousand, ninety-one".