21051077 has 4 divisors (see below), whose sum is σ = 21730176. Its totient is φ = 20371980.

The previous prime is 21051059. The next prime is 21051091. The reversal of 21051077 is 77015012.

It is a happy number.

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 21051077 - 2¹⁰ = 21050053 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 (21051047) 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, 339503 + ... + 339564.

It is an arithmetic number, because the mean of its divisors is an integer number (5432544).

Almost surely, 2^21051077 is an apocalyptic number.

It is an amenable number.

21051077 is a deficient number, since it is larger than the sum of its proper divisors (679099).

21051077 is an equidigital number, since it uses as much as digits as its factorization.

21051077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 679098.

The product of its (nonzero) digits is 490, while the sum is 23.

The square root of 21051077 is about 4588.1452679705. The cubic root of 21051077 is about 276.1159152189.

Adding to 21051077 its reverse (77015012), we get a palindrome (98066089).

The spelling of 21051077 in words is "twenty-one million, fifty-one thousand, seventy-seven".