21389155 has 8 divisors (see below), whose sum is σ = 27018000. Its totient is φ = 16210656.

The previous prime is 21389141. The next prime is 21389161. The reversal of 21389155 is 55198312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21389155 is a prime.

It is a super-2 number, since 2×21389155² = 914991903228050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21389155.

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, 112480 + ... + 112669.

It is an arithmetic number, because the mean of its divisors is an integer number (3377250).

Almost surely, 2^21389155 is an apocalyptic number.

21389155 is a deficient number, since it is larger than the sum of its proper divisors (5628845).

21389155 is a wasteful number, since it uses less digits than its factorization.

21389155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225173.

The product of its digits is 10800, while the sum is 34.

The square root of 21389155 is about 4624.8410783507. The cubic root of 21389155 is about 277.5862026919.

The spelling of 21389155 in words is "twenty-one million, three hundred eighty-nine thousand, one hundred fifty-five".