21450717 has 8 divisors (see below), whose sum is σ = 31778880. Its totient is φ = 14300460.

The previous prime is 21450707. The next prime is 21450727. The reversal of 21450717 is 71705412.

It is an interprime number because it is at equal distance from previous prime (21450707) and next prime (21450727).

It is not a de Polignac number, because 21450717 - 2⁴ = 21450701 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 794471 = 21450717 / (2 + 1 + 4 + 5 + 0 + 7 + 1 + 7).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450707) 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, 397209 + ... + 397262.

It is an arithmetic number, because the mean of its divisors is an integer number (3972360).

Almost surely, 2^21450717 is an apocalyptic number.

21450717 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21450717 is a deficient number, since it is larger than the sum of its proper divisors (10328163).

21450717 is an equidigital number, since it uses as much as digits as its factorization.

21450717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 794480 (or 794474 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 21450717 is about 4631.4918762749. The cubic root of 21450717 is about 277.8522626506.

The spelling of 21450717 in words is "twenty-one million, four hundred fifty thousand, seven hundred seventeen".