21431361 has 8 divisors (see below), whose sum is σ = 32657344. Its totient is φ = 12246480.

The previous prime is 21431359. The next prime is 21431383. The reversal of 21431361 is 16313412.

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

It is not a de Polignac number, because 21431361 - 2¹ = 21431359 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: 1020541 = 21431361 / (2 + 1 + 4 + 3 + 1 + 3 + 6 + 1).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21431341) 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, 510250 + ... + 510291.

It is an arithmetic number, because the mean of its divisors is an integer number (4082168).

Almost surely, 2^21431361 is an apocalyptic number.

21431361 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21431361 is a deficient number, since it is larger than the sum of its proper divisors (11225983).

21431361 is a wasteful number, since it uses less digits than its factorization.

21431361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020551.

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

The square root of 21431361 is about 4629.4017972088. The cubic root of 21431361 is about 277.7686644062.

Adding to 21431361 its reverse (16313412), we get a palindrome (37744773).

The spelling of 21431361 in words is "twenty-one million, four hundred thirty-one thousand, three hundred sixty-one".