21830761 has 2 divisors, whose sum is σ = 21830762. Its totient is φ = 21830760.

The previous prime is 21830759. The next prime is 21830773. The reversal of 21830761 is 16703812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21160000 + 670761 = 4600^2 + 819^2 .

It is a cyclic number.

It is not a de Polignac number, because 21830761 - 2¹ = 21830759 is a prime.

Together with 21830759, it forms a pair of twin primes.

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 (21833761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10915380 + 10915381.

It is an arithmetic number, because the mean of its divisors is an integer number (10915381).

Almost surely, 2^21830761 is an apocalyptic number.

It is an amenable number.

21830761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21830761 is an equidigital number, since it uses as much as digits as its factorization.

21830761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21830761 is about 4672.3399919098. The cubic root of 21830761 is about 279.4835761698.

The spelling of 21830761 in words is "twenty-one million, eight hundred thirty thousand, seven hundred sixty-one".