21862609 has 2 divisors, whose sum is σ = 21862610. Its totient is φ = 21862608.

The previous prime is 21862601. The next prime is 21862613. The reversal of 21862609 is 90626812.

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., 16443025 + 5419584 = 4055^2 + 2328^2 .

It is a cyclic number.

It is not a de Polignac number, because 21862609 - 2³ = 21862601 is a prime.

It is not a weakly prime, because it can be changed into another prime (21862601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10931304 + 10931305.

It is an arithmetic number, because the mean of its divisors is an integer number (10931305).

Almost surely, 2^21862609 is an apocalyptic number.

It is an amenable number.

21862609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21862609 is an equidigital number, since it uses as much as digits as its factorization.

21862609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 21862609 is about 4675.7468922088. The cubic root of 21862609 is about 279.6194191668.

The spelling of 21862609 in words is "twenty-one million, eight hundred sixty-two thousand, six hundred nine".