21354999 has 4 divisors (see below), whose sum is σ = 28473336. Its totient is φ = 14236664.

The previous prime is 21354989. The next prime is 21355003. The reversal of 21354999 is 99945312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21354999 - 2¹⁷ = 21223927 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21354999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21354959) 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, 3559164 + ... + 3559169.

It is an arithmetic number, because the mean of its divisors is an integer number (7118334).

Almost surely, 2^21354999 is an apocalyptic number.

21354999 is a deficient number, since it is larger than the sum of its proper divisors (7118337).

21354999 is an equidigital number, since it uses as much as digits as its factorization.

21354999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7118336.

The product of its digits is 87480, while the sum is 42.

The square root of 21354999 is about 4621.1469355562. The cubic root of 21354999 is about 277.4383663136.

The spelling of 21354999 in words is "twenty-one million, three hundred fifty-four thousand, nine hundred ninety-nine".