21870505 has 8 divisors (see below), whose sum is σ = 26500032. Its totient is φ = 17326128.

The previous prime is 21870473. The next prime is 21870547. The reversal of 21870505 is 50507812.

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

It is a cyclic number.

It is not a de Polignac number, because 21870505 - 2⁵ = 21870473 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20719 + ... + 21748.

It is an arithmetic number, because the mean of its divisors is an integer number (3312504).

Almost surely, 2^21870505 is an apocalyptic number.

It is an amenable number.

21870505 is a deficient number, since it is larger than the sum of its proper divisors (4629527).

21870505 is a wasteful number, since it uses less digits than its factorization.

21870505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42575.

The product of its (nonzero) digits is 2800, while the sum is 28.

The square root of 21870505 is about 4676.5911730661. The cubic root of 21870505 is about 279.6530779917.

The spelling of 21870505 in words is "twenty-one million, eight hundred seventy thousand, five hundred five".