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 a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12293977 = 103 ⋅119359.
It is a cyclic number.
It is a Duffinian number.
It is a congruent number.
It is a 4386-hyperperfect number.
Almost surely, 277939221 is an apocalyptic number.
It is an amenable number.
77939221 is an equidigital number, since it uses as much as digits as its factorization.
77939221 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 17770.
The square root of 77939221 is about 8828.3192624644. The cubic root of 77939221 is about 427.1548615876.
The spelling of 77939221 in words is "seventy-seven million, nine hundred thirty-nine thousand, two hundred twenty-one".