21307465 has 8 divisors (see below), whose sum is σ = 25822728. Its totient is φ = 16876800.

The previous prime is 21307457. The next prime is 21307469. The reversal of 21307465 is 56470312.

It can be written as a sum of positive squares in 4 ways, for example, as 7683984 + 13623481 = 2772^2 + 3691^2 .

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

It is not a de Polignac number, because 21307465 - 2³ = 21307457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21307469) 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, 20592 + ... + 21601.

It is an arithmetic number, because the mean of its divisors is an integer number (3227841).

Almost surely, 2^21307465 is an apocalyptic number.

It is an amenable number.

21307465 is a deficient number, since it is larger than the sum of its proper divisors (4515263).

21307465 is a wasteful number, since it uses less digits than its factorization.

21307465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42299.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21307465 is about 4616.0009748699. Note that the first 3 decimals coincide. The cubic root of 21307465 is about 277.2323637709.

Adding to 21307465 its reverse (56470312), we get a palindrome (77777777).

The spelling of 21307465 in words is "twenty-one million, three hundred seven thousand, four hundred sixty-five".