21077689 has 4 divisors (see below), whose sum is σ = 21219300. Its totient is φ = 20936080.

The previous prime is 21077659. The next prime is 21077741. The reversal of 21077689 is 98677012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1123600 + 19954089 = 1060^2 + 4467^2 .

It is a cyclic number.

It is not a de Polignac number, because 21077689 - 2⁷ = 21077561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21077629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70582 + ... + 70879.

It is an arithmetic number, because the mean of its divisors is an integer number (5304825).

Almost surely, 2^21077689 is an apocalyptic number.

It is an amenable number.

21077689 is a deficient number, since it is larger than the sum of its proper divisors (141611).

21077689 is a wasteful number, since it uses less digits than its factorization.

21077689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141610.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 21077689 is about 4591.0444345486. The cubic root of 21077689 is about 276.2322180975.

The spelling of 21077689 in words is "twenty-one million, seventy-seven thousand, six hundred eighty-nine".