21416765 has 4 divisors (see below), whose sum is σ = 25700124. Its totient is φ = 17133408.

The previous prime is 21416737. The next prime is 21416779. The reversal of 21416765 is 56761412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13271449 + 8145316 = 3643^2 + 2854^2 .

It is a cyclic number.

It is not a de Polignac number, because 21416765 - 2⁶ = 21416701 is a prime.

It is an alternating number because its digits alternate between even and odd.

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 3 ways as a sum of consecutive naturals, for example, 2141672 + ... + 2141681.

It is an arithmetic number, because the mean of its divisors is an integer number (6425031).

Almost surely, 2^21416765 is an apocalyptic number.

It is an amenable number.

21416765 is a deficient number, since it is larger than the sum of its proper divisors (4283359).

21416765 is an equidigital number, since it uses as much as digits as its factorization.

21416765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4283358.

The product of its digits is 10080, while the sum is 32.

The square root of 21416765 is about 4627.8250831249. The cubic root of 21416765 is about 277.7055912276.

The spelling of 21416765 in words is "twenty-one million, four hundred sixteen thousand, seven hundred sixty-five".