21623541 has 8 divisors (see below), whose sum is σ = 30527424. Its totient is φ = 13567680.

The previous prime is 21623533. The next prime is 21623551. The reversal of 21623541 is 14532612.

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

It is not a de Polignac number, because 21623541 - 2³ = 21623533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623551) 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, 211945 + ... + 212046.

It is an arithmetic number, because the mean of its divisors is an integer number (3815928).

Almost surely, 2^21623541 is an apocalyptic number.

It is an amenable number.

21623541 is a deficient number, since it is larger than the sum of its proper divisors (8903883).

21623541 is a wasteful number, since it uses less digits than its factorization.

21623541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424011.

The product of its digits is 1440, while the sum is 24.

The square root of 21623541 is about 4650.1119341366. Note that the first 3 decimals coincide. The cubic root of 21623541 is about 278.5964670272.

The spelling of 21623541 in words is "twenty-one million, six hundred twenty-three thousand, five hundred forty-one".