21500043 has 8 divisors (see below), whose sum is σ = 29333568. Its totient is φ = 13999944.

The previous prime is 21500029. The next prime is 21500069. The reversal of 21500043 is 34000512.

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

It is not a de Polignac number, because 21500043 - 2⁶ = 21499979 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21499995 and 21500031.

It is not an unprimeable number, because it can be changed into a prime (21500023) 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, 83205 + ... + 83462.

It is an arithmetic number, because the mean of its divisors is an integer number (3666696).

Almost surely, 2^21500043 is an apocalyptic number.

21500043 is a deficient number, since it is larger than the sum of its proper divisors (7833525).

21500043 is a wasteful number, since it uses less digits than its factorization.

21500043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166713.

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 21500043 is about 4636.8138845548. The cubic root of 21500043 is about 278.0650737025.

Adding to 21500043 its reverse (34000512), we get a palindrome (55500555).

The spelling of 21500043 in words is "twenty-one million, five hundred thousand, forty-three".