20406993 has 4 divisors (see below), whose sum is σ = 27209328. Its totient is φ = 13604660.

The previous prime is 20406989. The next prime is 20407019. The reversal of 20406993 is 39960402.

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 20406993 - 2² = 20406989 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20406973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3401163 + ... + 3401168.

It is an arithmetic number, because the mean of its divisors is an integer number (6802332).

Almost surely, 2^20406993 is an apocalyptic number.

It is an amenable number.

20406993 is a deficient number, since it is larger than the sum of its proper divisors (6802335).

20406993 is an equidigital number, since it uses as much as digits as its factorization.

20406993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6802334.

The product of its (nonzero) digits is 11664, while the sum is 33.

The square root of 20406993 is about 4517.4099880352. The cubic root of 20406993 is about 273.2706596670.

The spelling of 20406993 in words is "twenty million, four hundred six thousand, nine hundred ninety-three".