21727631 has 4 divisors (see below), whose sum is σ = 22051992. Its totient is φ = 21403272.

The previous prime is 21727619. The next prime is 21727637. The reversal of 21727631 is 13672712.

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 21727631 - 2⁶ = 21727567 is a prime.

It is a super-2 number, since 2×21727631² = 944179897744322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21727594 and 21727603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21727637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 162080 + ... + 162213.

It is an arithmetic number, because the mean of its divisors is an integer number (5512998).

Almost surely, 2^21727631 is an apocalyptic number.

21727631 is a deficient number, since it is larger than the sum of its proper divisors (324361).

21727631 is an equidigital number, since it uses as much as digits as its factorization.

21727631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324360.

The product of its digits is 3528, while the sum is 29.

The square root of 21727631 is about 4661.2907010827. The cubic root of 21727631 is about 279.0427815161.

The spelling of 21727631 in words is "twenty-one million, seven hundred twenty-seven thousand, six hundred thirty-one".