21451623 has 8 divisors (see below), whose sum is σ = 28633200. Its totient is φ = 14285568.

The previous prime is 21451621. The next prime is 21451631. The reversal of 21451623 is 32615412.

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

It is not a de Polignac number, because 21451623 - 2¹ = 21451621 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21451593 and 21451602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21451621) 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, 138 + ... + 6551.

It is an arithmetic number, because the mean of its divisors is an integer number (3579150).

Almost surely, 2^21451623 is an apocalyptic number.

21451623 is a deficient number, since it is larger than the sum of its proper divisors (7181577).

21451623 is a wasteful number, since it uses less digits than its factorization.

21451623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7761.

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

The square root of 21451623 is about 4631.5896838990. The cubic root of 21451623 is about 277.8561744174.

The spelling of 21451623 in words is "twenty-one million, four hundred fifty-one thousand, six hundred twenty-three".