20999601 has 16 divisors (see below), whose sum is σ = 35555200. Its totient is φ = 11999664.

The previous prime is 20999597. The next prime is 20999623. The reversal of 20999601 is 10699902.

It is not a de Polignac number, because 20999601 - 2² = 20999597 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20999651) 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 15 ways as a sum of consecutive naturals, for example, 55366 + ... + 55743.

It is an arithmetic number, because the mean of its divisors is an integer number (2222200).

Almost surely, 2^20999601 is an apocalyptic number.

20999601 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20999601 is a deficient number, since it is larger than the sum of its proper divisors (14555599).

20999601 is a wasteful number, since it uses less digits than its factorization.

20999601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111125 (or 111119 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 20999601 is about 4582.5321602799. The cubic root of 20999601 is about 275.8906703084.

The spelling of 20999601 in words is "twenty million, nine hundred ninety-nine thousand, six hundred one".