77021 has 4 divisors (see below), whose sum is σ = 88032. Its totient is φ = 66012.

The previous prime is 77017. The next prime is 77023. The reversal of 77021 is 12077.

It is a happy number.

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: 12077 = 13 ⋅929.

It is a cyclic number.

It is not a de Polignac number, because 77021 - 2² = 77017 is a prime.

It is a Curzon number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77023) 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, 5495 + ... + 5508.

It is an arithmetic number, because the mean of its divisors is an integer number (22008).

2⁷⁷⁰²¹ is an apocalyptic number.

It is an amenable number.

77021 is a deficient number, since it is larger than the sum of its proper divisors (11011).

77021 is a wasteful number, since it uses less digits than its factorization.

77021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11010.

The product of its (nonzero) digits is 98, while the sum is 17.

The square root of 77021 is about 277.5265753041. The cubic root of 77021 is about 42.5470758640.

Adding to 77021 its reverse (12077), we get a palindrome (89098).

The spelling of 77021 in words is "seventy-seven thousand, twenty-one", and thus it is an iban number.