21312145 has 8 divisors (see below), whose sum is σ = 26686656. Its totient is φ = 16308336.

The previous prime is 21312121. The next prime is 21312149. The reversal of 21312145 is 54121312.

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

It is a cyclic number.

It is not a de Polignac number, because 21312145 - 2⁵ = 21312113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21312149) 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, 92547 + ... + 92776.

It is an arithmetic number, because the mean of its divisors is an integer number (3335832).

Almost surely, 2^21312145 is an apocalyptic number.

It is an amenable number.

21312145 is a deficient number, since it is larger than the sum of its proper divisors (5374511).

21312145 is a wasteful number, since it uses less digits than its factorization.

21312145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185351.

The product of its digits is 240, while the sum is 19.

The square root of 21312145 is about 4616.5078793391. The cubic root of 21312145 is about 277.2526595136.

Adding to 21312145 its reverse (54121312), we get a palindrome (75433457).

The spelling of 21312145 in words is "twenty-one million, three hundred twelve thousand, one hundred forty-five".