77530821 has 4 divisors (see below), whose sum is σ = 103374432. Its totient is φ = 51687212.

The previous prime is 77530819. The next prime is 77530823. The reversal of 77530821 is 12803577.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12803577 = 3 ⋅4267859.

It is an interprime number because it is at equal distance from previous prime (77530819) and next prime (77530823).

It is a cyclic number.

It is not a de Polignac number, because 77530821 - 2¹ = 77530819 is a prime.

It is a super-2 number, since 2×77530821² = 12022056409868082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77530823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12921801 + ... + 12921806.

It is an arithmetic number, because the mean of its divisors is an integer number (25843608).

Almost surely, 2^77530821 is an apocalyptic number.

It is an amenable number.

77530821 is a deficient number, since it is larger than the sum of its proper divisors (25843611).

77530821 is a wasteful number, since it uses less digits than its factorization.

77530821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25843610.

The product of its (nonzero) digits is 11760, while the sum is 33.

The square root of 77530821 is about 8805.1587719927. The cubic root of 77530821 is about 426.4074602223.

The spelling of 77530821 in words is "seventy-seven million, five hundred thirty thousand, eight hundred twenty-one".