21403361 has 16 divisors (see below), whose sum is σ = 25740288. Its totient is φ = 17409600.

The previous prime is 21403337. The next prime is 21403399. The reversal of 21403361 is 16330412.

It is a de Polignac number, because none of the positive numbers 2^k-21403361 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21403061) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10571 + ... + 12431.

It is an arithmetic number, because the mean of its divisors is an integer number (1608768).

Almost surely, 2^21403361 is an apocalyptic number.

It is an amenable number.

21403361 is a deficient number, since it is larger than the sum of its proper divisors (4336927).

21403361 is a wasteful number, since it uses less digits than its factorization.

21403361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1952.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 21403361 is about 4626.3766599792. The cubic root of 21403361 is about 277.6476437492.

Adding to 21403361 its reverse (16330412), we get a palindrome (37733773).

The spelling of 21403361 in words is "twenty-one million, four hundred three thousand, three hundred sixty-one".