21330761 has 2 divisors, whose sum is σ = 21330762. Its totient is φ = 21330760.

The previous prime is 21330737. The next prime is 21330781. The reversal of 21330761 is 16703312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13801225 + 7529536 = 3715^2 + 2744^2 .

It is a cyclic number.

It is not a de Polignac number, because 21330761 - 2¹⁸ = 21068617 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21330781) 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, 10665380 + 10665381.

It is an arithmetic number, because the mean of its divisors is an integer number (10665381).

Almost surely, 2^21330761 is an apocalyptic number.

It is an amenable number.

21330761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21330761 is an equidigital number, since it uses as much as digits as its factorization.

21330761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 21330761 is about 4618.5236818706. The cubic root of 21330761 is about 277.3333620652. Note that the first 4 decimals are identical.

The spelling of 21330761 in words is "twenty-one million, three hundred thirty thousand, seven hundred sixty-one".