77681521 has 8 divisors (see below), whose sum is σ = 79801920. Its totient is φ = 75575472.

The previous prime is 77681507. The next prime is 77681543. The reversal of 77681521 is 12518677.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 77681521 - 2¹¹ = 77679473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77681561) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7875 + ... + 14743.

It is an arithmetic number, because the mean of its divisors is an integer number (9975240).

Almost surely, 2^77681521 is an apocalyptic number.

It is an amenable number.

77681521 is a deficient number, since it is larger than the sum of its proper divisors (2120399).

77681521 is a wasteful number, since it uses less digits than its factorization.

77681521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7175.

The product of its digits is 23520, while the sum is 37.

The square root of 77681521 is about 8813.7121010389. The cubic root of 77681521 is about 426.6835569350.

The spelling of 77681521 in words is "seventy-seven million, six hundred eighty-one thousand, five hundred twenty-one".