21386865 has 8 divisors (see below), whose sum is σ = 34219008. Its totient is φ = 11406320.

The previous prime is 21386863. The next prime is 21386879. The reversal of 21386865 is 56868312.

It is a happy number.

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

It is not a de Polignac number, because 21386865 - 2¹ = 21386863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21386861) 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, 712881 + ... + 712910.

It is an arithmetic number, because the mean of its divisors is an integer number (4277376).

Almost surely, 2^21386865 is an apocalyptic number.

It is an amenable number.

21386865 is a deficient number, since it is larger than the sum of its proper divisors (12832143).

21386865 is a wasteful number, since it uses less digits than its factorization.

21386865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1425799.

The product of its digits is 69120, while the sum is 39.

The square root of 21386865 is about 4624.5934956491. The cubic root of 21386865 is about 277.5762958787.

It can be divided in two parts, 213 and 86865, that added together give a palindrome (87078).

The spelling of 21386865 in words is "twenty-one million, three hundred eighty-six thousand, eight hundred sixty-five".