21451465 has 12 divisors (see below), whose sum is σ = 29944836. Its totient is φ = 14709408.

The previous prime is 21451459. The next prime is 21451471. The reversal of 21451465 is 56415412.

It is an interprime number because it is at equal distance from previous prime (21451459) and next prime (21451471).

It can be written as a sum of positive squares in 2 ways, for example, as 3337929 + 18113536 = 1827^2 + 4256^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21451465 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43534 + ... + 44023.

It is an arithmetic number, because the mean of its divisors is an integer number (2495403).

Almost surely, 2^21451465 is an apocalyptic number.

It is an amenable number.

21451465 is a deficient number, since it is larger than the sum of its proper divisors (8493371).

21451465 is an equidigital number, since it uses as much as digits as its factorization.

21451465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87576 (or 87569 counting only the distinct ones).

The product of its digits is 4800, while the sum is 28.

The square root of 21451465 is about 4631.5726270890. The cubic root of 21451465 is about 277.8554922408.

Adding to 21451465 its reverse (56415412), we get a palindrome (77866877).

The spelling of 21451465 in words is "twenty-one million, four hundred fifty-one thousand, four hundred sixty-five".