20993957 has 4 divisors (see below), whose sum is σ = 21031296. Its totient is φ = 20956620.

The previous prime is 20993953. The next prime is 20993971. The reversal of 20993957 is 75939902.

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 20993957 - 2² = 20993953 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20993953) 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, 17813 + ... + 18954.

It is an arithmetic number, because the mean of its divisors is an integer number (5257824).

Almost surely, 2^20993957 is an apocalyptic number.

It is an amenable number.

20993957 is a deficient number, since it is larger than the sum of its proper divisors (37339).

20993957 is an equidigital number, since it uses as much as digits as its factorization.

20993957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37338.

The product of its (nonzero) digits is 153090, while the sum is 44.

The square root of 20993957 is about 4581.9163021600. The cubic root of 20993957 is about 275.8659513234.

The spelling of 20993957 in words is "twenty million, nine hundred ninety-three thousand, nine hundred fifty-seven".