21717601 has 2 divisors, whose sum is σ = 21717602. Its totient is φ = 21717600.

The previous prime is 21717599. The next prime is 21717613. The reversal of 21717601 is 10671712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15210000 + 6507601 = 3900^2 + 2551^2 .

It is a cyclic number.

It is not a de Polignac number, because 21717601 - 2¹ = 21717599 is a prime.

It is a super-3 number, since 3×21717601³ (a number of 23 digits) contains 333 as substring.

Together with 21717599, it forms a pair of twin primes.

It is a weakly prime.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858800 + 10858801.

It is an arithmetic number, because the mean of its divisors is an integer number (10858801).

Almost surely, 2^21717601 is an apocalyptic number.

It is an amenable number.

21717601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717601 is an equidigital number, since it uses as much as digits as its factorization.

21717601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 588, while the sum is 25.

The square root of 21717601 is about 4660.2146946251. The cubic root of 21717601 is about 278.9998372750. Note that the first 3 decimals are identical.

The spelling of 21717601 in words is "twenty-one million, seven hundred seventeen thousand, six hundred one".