77990221 has 8 divisors (see below), whose sum is σ = 78750360. Its totient is φ = 77233728.

The previous prime is 77990219. The next prime is 77990233. The reversal of 77990221 is 12209977.

It can be written as a sum of positive squares in 4 ways, for example, as 3944196 + 74046025 = 1986^2 + 8605^2 .

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 77990221 - 2¹ = 77990219 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 (77990201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60435 + ... + 61711.

It is an arithmetic number, because the mean of its divisors is an integer number (9843795).

Almost surely, 2^77990221 is an apocalyptic number.

It is an amenable number.

77990221 is a deficient number, since it is larger than the sum of its proper divisors (760139).

77990221 is a wasteful number, since it uses less digits than its factorization.

77990221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1823.

The product of its (nonzero) digits is 15876, while the sum is 37.

The square root of 77990221 is about 8831.2072221186. The cubic root of 77990221 is about 427.2480117273.

The spelling of 77990221 in words is "seventy-seven million, nine hundred ninety thousand, two hundred twenty-one".