21630407 has 4 divisors (see below), whose sum is σ = 21710496. Its totient is φ = 21550320.

The previous prime is 21630391. The next prime is 21630421. The reversal of 21630407 is 70403612.

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

It is a cyclic number.

It is not a de Polignac number, because 21630407 - 2⁴ = 21630391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630457) 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, 39638 + ... + 40179.

It is an arithmetic number, because the mean of its divisors is an integer number (5427624).

Almost surely, 2^21630407 is an apocalyptic number.

21630407 is a deficient number, since it is larger than the sum of its proper divisors (80089).

21630407 is an equidigital number, since it uses as much as digits as its factorization.

21630407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80088.

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 21630407 is about 4650.8501373405. The cubic root of 21630407 is about 278.6259509574.

The spelling of 21630407 in words is "twenty-one million, six hundred thirty thousand, four hundred seven".