21857069 has 8 divisors (see below), whose sum is σ = 23690520. Its totient is φ = 20045376.

The previous prime is 21857063. The next prime is 21857071. The reversal of 21857069 is 96075812.

It can be written as a sum of positive squares in 4 ways, for example, as 3108169 + 18748900 = 1763^2 + 4330^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-21857069 is a prime.

It is a super-2 number, since 2×21857069² = 955462930541522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21857063) 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, 3314 + ... + 7395.

It is an arithmetic number, because the mean of its divisors is an integer number (2961315).

Almost surely, 2^21857069 is an apocalyptic number.

It is an amenable number.

21857069 is a deficient number, since it is larger than the sum of its proper divisors (1833451).

21857069 is a wasteful number, since it uses less digits than its factorization.

21857069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10879.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21857069 is about 4675.1544359518. The cubic root of 21857069 is about 279.5957985878.

The spelling of 21857069 in words is "twenty-one million, eight hundred fifty-seven thousand, sixty-nine".