20993869 has 4 divisors (see below), whose sum is σ = 22608796. Its totient is φ = 19378944.

The previous prime is 20993857. The next prime is 20993873. The reversal of 20993869 is 96839902.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9180900 + 11812969 = 3030^2 + 3437^2 .

It is not a de Polignac number, because 20993869 - 2⁷ = 20993741 is a prime.

It is a super-2 number, since 2×20993869² = 881485071178322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20993839) 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, 807444 + ... + 807469.

It is an arithmetic number, because the mean of its divisors is an integer number (5652199).

Almost surely, 2^20993869 is an apocalyptic number.

It is an amenable number.

20993869 is a deficient number, since it is larger than the sum of its proper divisors (1614927).

20993869 is a wasteful number, since it uses less digits than its factorization.

20993869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1614926.

The product of its (nonzero) digits is 209952, while the sum is 46.

The square root of 20993869 is about 4581.9066991810. The cubic root of 20993869 is about 275.8655658754.

The spelling of 20993869 in words is "twenty million, nine hundred ninety-three thousand, eight hundred sixty-nine".