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77939221 = 78839887

77939221 has 4 divisors (see below), whose sum is σ = 77956992. Its totient is φ = 77921452.

The previous prime is 77939189. The next prime is 77939231. The reversal of 77939221 is 12293977.

It can be divided in two parts, 779 and 39221, that added together give a square (40000 = 2002).

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 = 103119359.

It is a cyclic number.

It is not a de Polignac number, because 77939221 - 25 = 77939189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77939231) 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, 2940 + ... + 12826.

It is an arithmetic number, because the mean of its divisors is an integer number (19489248).

It is a 4386-hyperperfect number.

Almost surely, 277939221 is an apocalyptic number.

It is an amenable number.

77939221 is a deficient number, since it is larger than the sum of its proper divisors (17771).

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 product of its digits is 47628, while the sum is 40.

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".

Divisors: 1 7883 9887 77939221