21378693 has 16 divisors (see below), whose sum is σ = 32681600. Its totient is φ = 12177216.

The previous prime is 21378691. The next prime is 21378701. The reversal of 21378693 is 39687312.

It is not a de Polignac number, because 21378693 - 2¹ = 21378691 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21378691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5871 + ... + 8787.

It is an arithmetic number, because the mean of its divisors is an integer number (2042600).

Almost surely, 2^21378693 is an apocalyptic number.

It is an amenable number.

21378693 is a deficient number, since it is larger than the sum of its proper divisors (11302907).

21378693 is a wasteful number, since it uses less digits than its factorization.

21378693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3276.

The product of its digits is 54432, while the sum is 39.

The square root of 21378693 is about 4623.7098741162. The cubic root of 21378693 is about 277.5409370659.

The spelling of 21378693 in words is "twenty-one million, three hundred seventy-eight thousand, six hundred ninety-three".