21206703 has 8 divisors (see below), whose sum is σ = 32315008. Its totient is φ = 12118104.

The previous prime is 21206699. The next prime is 21206747. The reversal of 21206703 is 30760212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21206703 - 2² = 21206699 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 1009843 = 21206703 / (2 + 1 + 2 + 0 + 6 + 7 + 0 + 3).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21206703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206753) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 504901 + ... + 504942.

It is an arithmetic number, because the mean of its divisors is an integer number (4039376).

Almost surely, 2^21206703 is an apocalyptic number.

21206703 is a deficient number, since it is larger than the sum of its proper divisors (11108305).

21206703 is a wasteful number, since it uses less digits than its factorization.

21206703 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1009853.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21206703 is about 4605.0736150468. The cubic root of 21206703 is about 276.7946668243.

Adding to 21206703 its reverse (30760212), we get a palindrome (51966915).

The spelling of 21206703 in words is "twenty-one million, two hundred six thousand, seven hundred three".