21018077 has 4 divisors (see below), whose sum is σ = 21222240. Its totient is φ = 20813916.

The previous prime is 21018073. The next prime is 21018079. The reversal of 21018077 is 77081012.

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.

It is a cyclic number.

It is not a de Polignac number, because 21018077 - 2² = 21018073 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 (21018073) 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, 101927 + ... + 102132.

It is an arithmetic number, because the mean of its divisors is an integer number (5305560).

Almost surely, 2^21018077 is an apocalyptic number.

It is an amenable number.

21018077 is a deficient number, since it is larger than the sum of its proper divisors (204163).

21018077 is a wasteful number, since it uses less digits than its factorization.

21018077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204162.

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 21018077 is about 4584.5476330822. The cubic root of 21018077 is about 275.9715585409.

Adding to 21018077 its reverse (77081012), we get a palindrome (98099089).

The spelling of 21018077 in words is "twenty-one million, eighteen thousand, seventy-seven".