21690343 has 4 divisors (see below), whose sum is σ = 22831960. Its totient is φ = 20548728.

The previous prime is 21690337. The next prime is 21690349. The reversal of 21690343 is 34309612.

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

It is an interprime number because it is at equal distance from previous prime (21690337) and next prime (21690349).

It is not a de Polignac number, because 21690343 - 2¹³ = 21682151 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 570780 + ... + 570817.

It is an arithmetic number, because the mean of its divisors is an integer number (5707990).

Almost surely, 2^21690343 is an apocalyptic number.

21690343 is a deficient number, since it is larger than the sum of its proper divisors (1141617).

21690343 is a wasteful number, since it uses less digits than its factorization.

21690343 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1141616.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 21690343 is about 4657.2892330196. The cubic root of 21690343 is about 278.8830631513.

Adding to 21690343 its reverse (34309612), we get a palindrome (55999955).

The spelling of 21690343 in words is "twenty-one million, six hundred ninety thousand, three hundred forty-three".