21053631 has 8 divisors (see below), whose sum is σ = 28120624. Its totient is φ = 14011200.

The previous prime is 21053609. The next prime is 21053639. The reversal of 21053631 is 13635012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21053631 - 2⁶ = 21053567 is a prime.

It is a super-2 number, since 2×21053631² = 886510756568322, 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 = 21053598 and 21053607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4036 + ... + 7641.

It is an arithmetic number, because the mean of its divisors is an integer number (3515078).

Almost surely, 2^21053631 is an apocalyptic number.

21053631 is a deficient number, since it is larger than the sum of its proper divisors (7066993).

21053631 is a wasteful number, since it uses less digits than its factorization.

21053631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12281.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21053631 is about 4588.4235855030. The cubic root of 21053631 is about 276.1270812594.

Adding to 21053631 its reverse (13635012), we get a palindrome (34688643).

The spelling of 21053631 in words is "twenty-one million, fifty-three thousand, six hundred thirty-one".