21623998 has 8 divisors (see below), whose sum is σ = 35384760. Its totient is φ = 9829080.

The previous prime is 21623993. The next prime is 21624011. The reversal of 21623998 is 89932612.

It is a happy number.

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

It is a super-3 number, since 3×21623998³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21623998.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 491433 + ... + 491476.

It is an arithmetic number, because the mean of its divisors is an integer number (4423095).

Almost surely, 2^21623998 is an apocalyptic number.

21623998 is a deficient number, since it is larger than the sum of its proper divisors (13760762).

21623998 is a wasteful number, since it uses less digits than its factorization.

21623998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 982922.

The product of its digits is 46656, while the sum is 40.

The square root of 21623998 is about 4650.1610724791. The cubic root of 21623998 is about 278.5984296673.

The spelling of 21623998 in words is "twenty-one million, six hundred twenty-three thousand, nine hundred ninety-eight".