21450643 has 4 divisors (see below), whose sum is σ = 21460120. Its totient is φ = 21441168.

The previous prime is 21450641. The next prime is 21450647. The reversal of 21450643 is 34605412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21450643 - 2¹ = 21450641 is a prime.

It is a super-2 number, since 2×21450643² = 920260170226898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21450641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 871 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (5365030).

Almost surely, 2^21450643 is an apocalyptic number.

21450643 is a deficient number, since it is larger than the sum of its proper divisors (9477).

21450643 is an equidigital number, since it uses as much as digits as its factorization.

21450643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9476.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21450643 is about 4631.4838874814. The cubic root of 21450643 is about 277.8519431416.

The spelling of 21450643 in words is "twenty-one million, four hundred fifty thousand, six hundred forty-three".