77320421 has 8 divisors (see below), whose sum is σ = 78132600. Its totient is φ = 76512448.

The previous prime is 77320391. The next prime is 77320427. The reversal of 77320421 is 12402377.

It can be written as a sum of positive squares in 4 ways, for example, as 11937025 + 65383396 = 3455^2 + 8086^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 77320421 - 2⁶ = 77320357 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 (77320427) 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, 46415 + ... + 48051.

It is an arithmetic number, because the mean of its divisors is an integer number (9766575).

Almost surely, 2^77320421 is an apocalyptic number.

It is an amenable number.

77320421 is a deficient number, since it is larger than the sum of its proper divisors (812179).

77320421 is a wasteful number, since it uses less digits than its factorization.

77320421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2103.

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 77320421 is about 8793.2031137692. The cubic root of 77320421 is about 426.0213883477.

Adding to 77320421 its reverse (12402377), we get a palindrome (89722798).

The spelling of 77320421 in words is "seventy-seven million, three hundred twenty thousand, four hundred twenty-one".