21631430 has 16 divisors (see below), whose sum is σ = 39066624. Its totient is φ = 8623680.

The previous prime is 21631409. The next prime is 21631439. The reversal of 21631430 is 3413612.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631439) 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, 326 + ... + 6585.

It is an arithmetic number, because the mean of its divisors is an integer number (2441664).

Almost surely, 2^21631430 is an apocalyptic number.

21631430 is a deficient number, since it is larger than the sum of its proper divisors (17435194).

21631430 is a wasteful number, since it uses less digits than its factorization.

21631430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7231.

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 21631430 is about 4650.9601159331. The cubic root of 21631430 is about 278.6303433829.

The spelling of 21631430 in words is "twenty-one million, six hundred thirty-one thousand, four hundred thirty".