21403090 has 8 divisors (see below), whose sum is σ = 38525580. Its totient is φ = 8561232.

The previous prime is 21403079. The next prime is 21403097. The reversal of 21403090 is 9030412.

It can be written as a sum of positive squares in 2 ways, for example, as 18344089 + 3059001 = 4283^2 + 1749^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21403097) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1070145 + ... + 1070164.

Almost surely, 2^21403090 is an apocalyptic number.

21403090 is a deficient number, since it is larger than the sum of its proper divisors (17122490).

21403090 is a wasteful number, since it uses less digits than its factorization.

21403090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2140316.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21403090 is about 4626.3473713071. The cubic root of 21403090 is about 277.6464719265.

The spelling of 21403090 in words is "twenty-one million, four hundred three thousand, ninety".