21310405 has 8 divisors (see below), whose sum is σ = 25657632. Its totient is φ = 16991568.

The previous prime is 21310337. The next prime is 21310417. The reversal of 21310405 is 50401312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21310405 is a prime.

It is a super-2 number, since 2×21310405² = 908266722528050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5407 + ... + 8476.

It is an arithmetic number, because the mean of its divisors is an integer number (3207204).

Almost surely, 2^21310405 is an apocalyptic number.

It is an amenable number.

21310405 is a deficient number, since it is larger than the sum of its proper divisors (4347227).

21310405 is a wasteful number, since it uses less digits than its factorization.

21310405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14195.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21310405 is about 4616.3194213572. The cubic root of 21310405 is about 277.2451140076.

Adding to 21310405 its reverse (50401312), we get a palindrome (71711717).

The spelling of 21310405 in words is "twenty-one million, three hundred ten thousand, four hundred five".