21690503 has 4 divisors (see below), whose sum is σ = 21703968. Its totient is φ = 21677040.

The previous prime is 21690499. The next prime is 21690523. The reversal of 21690503 is 30509612.

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

It is a cyclic number.

It is not a de Polignac number, because 21690503 - 2² = 21690499 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 (21690523) 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, 3926 + ... + 7667.

It is an arithmetic number, because the mean of its divisors is an integer number (5425992).

Almost surely, 2^21690503 is an apocalyptic number.

21690503 is a deficient number, since it is larger than the sum of its proper divisors (13465).

21690503 is a wasteful number, since it uses less digits than its factorization.

21690503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13464.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 21690503 is about 4657.3064103621. The cubic root of 21690503 is about 278.8837488816.

The spelling of 21690503 in words is "twenty-one million, six hundred ninety thousand, five hundred three".