77491987 has 4 divisors (see below), whose sum is σ = 77524216. Its totient is φ = 77459760.

The previous prime is 77491979. The next prime is 77492011. The reversal of 77491987 is 78919477.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 77491987 - 2³ = 77491979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77491907) 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, 12189 + ... + 17422.

It is an arithmetic number, because the mean of its divisors is an integer number (19381054).

Almost surely, 2^77491987 is an apocalyptic number.

77491987 is a deficient number, since it is larger than the sum of its proper divisors (32229).

77491987 is a wasteful number, since it uses less digits than its factorization.

77491987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32228.

The product of its digits is 889056, while the sum is 52.

The square root of 77491987 is about 8802.9533112473. The cubic root of 77491987 is about 426.3362546785.

The spelling of 77491987 in words is "seventy-seven million, four hundred ninety-one thousand, nine hundred eighty-seven".