21431653 has 4 divisors (see below), whose sum is σ = 22363488. Its totient is φ = 20499820.

The previous prime is 21431647. The next prime is 21431681. The reversal of 21431653 is 35613412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21431653 - 2⁹ = 21431141 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 (21431623) 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 3 ways as a sum of consecutive naturals, for example, 465883 + ... + 465928.

It is an arithmetic number, because the mean of its divisors is an integer number (5590872).

Almost surely, 2^21431653 is an apocalyptic number.

21431653 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21431653 is a deficient number, since it is larger than the sum of its proper divisors (931835).

21431653 is an equidigital number, since it uses as much as digits as its factorization.

21431653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 931834.

The product of its digits is 2160, while the sum is 25.

The square root of 21431653 is about 4629.4333346534. The cubic root of 21431653 is about 277.7699259232.

It can be divided in two parts, 214316 and 53, that added together give a square (214369 = 463²).

The spelling of 21431653 in words is "twenty-one million, four hundred thirty-one thousand, six hundred fifty-three".