77630921 has 4 divisors (see below), whose sum is σ = 79729092. Its totient is φ = 75532752.

The previous prime is 77630899. The next prime is 77630929. The reversal of 77630921 is 12903677.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12903677 = 467 ⋅27631.

It can be written as a sum of positive squares in 2 ways, for example, as 72505225 + 5125696 = 8515^2 + 2264^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77630921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77630929) 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 3 ways as a sum of consecutive naturals, for example, 1049030 + ... + 1049103.

It is an arithmetic number, because the mean of its divisors is an integer number (19932273).

Almost surely, 2^77630921 is an apocalyptic number.

It is an amenable number.

77630921 is a deficient number, since it is larger than the sum of its proper divisors (2098171).

77630921 is a wasteful number, since it uses less digits than its factorization.

77630921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2098170.

The product of its (nonzero) digits is 15876, while the sum is 35.

The square root of 77630921 is about 8810.8411062736. The cubic root of 77630921 is about 426.5908927802.

The spelling of 77630921 in words is "seventy-seven million, six hundred thirty thousand, nine hundred twenty-one".