21385455 has 32 divisors (see below), whose sum is σ = 42115584. Its totient is φ = 9023616.

The previous prime is 21385453. The next prime is 21385459. The reversal of 21385455 is 55458312.

It is not a de Polignac number, because 21385455 - 2¹ = 21385453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21385453) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6469 + ... + 9198.

It is an arithmetic number, because the mean of its divisors is an integer number (1316112).

Almost surely, 2^21385455 is an apocalyptic number.

21385455 is a deficient number, since it is larger than the sum of its proper divisors (20730129).

21385455 is a wasteful number, since it uses less digits than its factorization.

21385455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15695.

The product of its digits is 24000, while the sum is 33.

The square root of 21385455 is about 4624.4410473051. The cubic root of 21385455 is about 277.5701956987.

The spelling of 21385455 in words is "twenty-one million, three hundred eighty-five thousand, four hundred fifty-five".