77777777021 has 8 divisors (see below), whose sum is σ = 88895393664. Its totient is φ = 66661786800.

The previous prime is 77777777003. The next prime is 77777777089. The reversal of 77777777021 is 12077777777.

It is a happy number.

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

It is not a de Polignac number, because 77777777021 - 2³⁴ = 60597907837 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77777779021) 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, 302345 + ... + 496958.

It is an arithmetic number, because the mean of its divisors is an integer number (11111924208).

Almost surely, 2^77777777021 is an apocalyptic number.

It is an amenable number.

77777777021 is a deficient number, since it is larger than the sum of its proper divisors (11117616643).

77777777021 is a wasteful number, since it uses less digits than its factorization.

77777777021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813211.

The product of its (nonzero) digits is 11529602, while the sum is 59.

The spelling of 77777777021 in words is "seventy-seven billion, seven hundred seventy-seven million, seven hundred seventy-seven thousand, twenty-one".