21661203 has 8 divisors (see below), whose sum is σ = 28903888. Its totient is φ = 14429664.

The previous prime is 21661183. The next prime is 21661223. The reversal of 21661203 is 30216612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21661183) and next prime (21661223).

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

It is not a de Polignac number, because 21661203 - 2¹³ = 21653011 is a prime.

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 21661203.

It is not an unprimeable number, because it can be changed into a prime (21661223) 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, 4401 + ... + 7917.

It is an arithmetic number, because the mean of its divisors is an integer number (3612986).

Almost surely, 2^21661203 is an apocalyptic number.

21661203 is a deficient number, since it is larger than the sum of its proper divisors (7242685).

21661203 is a wasteful number, since it uses less digits than its factorization.

21661203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5573.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21661203 is about 4654.1597523076. The cubic root of 21661203 is about 278.7581182323.

Adding to 21661203 its reverse (30216612), we get a palindrome (51877815).

The spelling of 21661203 in words is "twenty-one million, six hundred sixty-one thousand, two hundred three".