21378411 has 12 divisors (see below), whose sum is σ = 32023992. Its totient is φ = 14252112.

The previous prime is 21378407. The next prime is 21378419. The reversal of 21378411 is 11487312.

It is not a de Polignac number, because 21378411 - 2² = 21378407 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21378419) 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 11 ways as a sum of consecutive naturals, for example, 43746 + ... + 44231.

It is an arithmetic number, because the mean of its divisors is an integer number (2668666).

Almost surely, 2^21378411 is an apocalyptic number.

21378411 is a deficient number, since it is larger than the sum of its proper divisors (10645581).

21378411 is an frugal number, since it uses more digits than its factorization.

21378411 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87992 (or 87980 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 21378411 is about 4623.6793790227. The cubic root of 21378411 is about 277.5397167405.

The spelling of 21378411 in words is "twenty-one million, three hundred seventy-eight thousand, four hundred eleven".