21126577 has 4 divisors (see below), whose sum is σ = 21293056. Its totient is φ = 20960100.

The previous prime is 21126569. The next prime is 21126583. The reversal of 21126577 is 77562112.

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 21126577 - 2³ = 21126569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21126517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 83049 + ... + 83302.

It is an arithmetic number, because the mean of its divisors is an integer number (5323264).

Almost surely, 2^21126577 is an apocalyptic number.

It is an amenable number.

21126577 is a deficient number, since it is larger than the sum of its proper divisors (166479).

21126577 is a wasteful number, since it uses less digits than its factorization.

21126577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166478.

The product of its digits is 5880, while the sum is 31.

The square root of 21126577 is about 4596.3656294947. The cubic root of 21126577 is about 276.4456193119.

Adding to 21126577 its reverse (77562112), we get a palindrome (98688689).

The spelling of 21126577 in words is "twenty-one million, one hundred twenty-six thousand, five hundred seventy-seven".