21671653 has 8 divisors (see below), whose sum is σ = 22498560. Its totient is φ = 20860080.

The previous prime is 21671633. The next prime is 21671669. The reversal of 21671653 is 35617612.

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

It is a cyclic number.

It is not a de Polignac number, because 21671653 - 2²¹ = 19574501 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 (21671623) 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, 913 + ... + 6646.

It is an arithmetic number, because the mean of its divisors is an integer number (2812320).

Almost surely, 2^21671653 is an apocalyptic number.

It is an amenable number.

21671653 is a deficient number, since it is larger than the sum of its proper divisors (826907).

21671653 is an equidigital number, since it uses as much as digits as its factorization.

21671653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7667.

The product of its digits is 7560, while the sum is 31.

The square root of 21671653 is about 4655.2822685633. The cubic root of 21671653 is about 278.8029380579.

The spelling of 21671653 in words is "twenty-one million, six hundred seventy-one thousand, six hundred fifty-three".