21760261 has 2 divisors, whose sum is σ = 21760262. Its totient is φ = 21760260.

The previous prime is 21760247. The next prime is 21760303. The reversal of 21760261 is 16206712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19492225 + 2268036 = 4415^2 + 1506^2 .

It is a cyclic number.

It is not a de Polignac number, because 21760261 - 2⁷ = 21760133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21764261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10880130 + 10880131.

It is an arithmetic number, because the mean of its divisors is an integer number (10880131).

Almost surely, 2^21760261 is an apocalyptic number.

It is an amenable number.

21760261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21760261 is an equidigital number, since it uses as much as digits as its factorization.

21760261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21760261 is about 4664.7894914991. The cubic root of 21760261 is about 279.1823980838.

Adding to 21760261 its reverse (16206712), we get a palindrome (37966973).

The spelling of 21760261 in words is "twenty-one million, seven hundred sixty thousand, two hundred sixty-one".