21906601 has 4 divisors (see below), whose sum is σ = 23059600. Its totient is φ = 20753604.

The previous prime is 21906593. The next prime is 21906607. The reversal of 21906601 is 10660912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21906601 - 2³ = 21906593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21906607) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 576471 + ... + 576508.

It is an arithmetic number, because the mean of its divisors is an integer number (5764900).

Almost surely, 2^21906601 is an apocalyptic number.

It is an amenable number.

21906601 is a deficient number, since it is larger than the sum of its proper divisors (1152999).

21906601 is a wasteful number, since it uses less digits than its factorization.

21906601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1152998.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 21906601 is about 4680.4488032666. The cubic root of 21906601 is about 279.8068438239.

The spelling of 21906601 in words is "twenty-one million, nine hundred six thousand, six hundred one".