21230761 has 2 divisors, whose sum is σ = 21230762. Its totient is φ = 21230760.

The previous prime is 21230749. The next prime is 21230767. The reversal of 21230761 is 16703212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15848361 + 5382400 = 3981^2 + 2320^2 .

It is a cyclic number.

It is not a de Polignac number, because 21230761 - 2⁹ = 21230249 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21230767) 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 as a sum of consecutive naturals, namely, 10615380 + 10615381.

It is an arithmetic number, because the mean of its divisors is an integer number (10615381).

Almost surely, 2^21230761 is an apocalyptic number.

It is an amenable number.

21230761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21230761 is an equidigital number, since it uses as much as digits as its factorization.

21230761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21230761 is about 4607.6849935732. The cubic root of 21230761 is about 276.8992974140.

Adding to 21230761 its reverse (16703212), we get a palindrome (37933973).

The spelling of 21230761 in words is "twenty-one million, two hundred thirty thousand, seven hundred sixty-one".