21136461 has 4 divisors (see below), whose sum is σ = 28181952. Its totient is φ = 14090972.

The previous prime is 21136441. The next prime is 21136463. The reversal of 21136461 is 16463112.

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 21136461 - 2⁵ = 21136429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21136463) 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, 3522741 + ... + 3522746.

It is an arithmetic number, because the mean of its divisors is an integer number (7045488).

Almost surely, 2^21136461 is an apocalyptic number.

It is an amenable number.

21136461 is a deficient number, since it is larger than the sum of its proper divisors (7045491).

21136461 is an equidigital number, since it uses as much as digits as its factorization.

21136461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7045490.

The product of its digits is 864, while the sum is 24.

The square root of 21136461 is about 4597.4407010858. The cubic root of 21136461 is about 276.4887239836.

Adding to 21136461 its reverse (16463112), we get a palindrome (37599573).

The spelling of 21136461 in words is "twenty-one million, one hundred thirty-six thousand, four hundred sixty-one".