21490403 has 4 divisors (see below), whose sum is σ = 23444088. Its totient is φ = 19536720.

The previous prime is 21490393. The next prime is 21490423. The reversal of 21490403 is 30409412.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21490403 is a prime.

It is a super-2 number, since 2×21490403² = 923674842204818, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21490423) 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, 976826 + ... + 976847.

It is an arithmetic number, because the mean of its divisors is an integer number (5861022).

Almost surely, 2^21490403 is an apocalyptic number.

21490403 is a deficient number, since it is larger than the sum of its proper divisors (1953685).

21490403 is a wasteful number, since it uses less digits than its factorization.

21490403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1953684.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21490403 is about 4635.7742611132. The cubic root of 21490403 is about 278.0235086998.

Adding to 21490403 its reverse (30409412), we get a palindrome (51899815).

The spelling of 21490403 in words is "twenty-one million, four hundred ninety thousand, four hundred three".