21421378 has 16 divisors (see below), whose sum is σ = 35800704. Its totient is φ = 9529360.

The previous prime is 21421373. The next prime is 21421397. The reversal of 21421378 is 87312412.

It is not an unprimeable number, because it can be changed into a prime (21421373) 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, 9325 + ... + 11392.

It is an arithmetic number, because the mean of its divisors is an integer number (2237544).

Almost surely, 2^21421378 is an apocalyptic number.

21421378 is a deficient number, since it is larger than the sum of its proper divisors (14379326).

21421378 is a wasteful number, since it uses less digits than its factorization.

21421378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20777.

The product of its digits is 2688, while the sum is 28.

The square root of 21421378 is about 4628.3234545567. The cubic root of 21421378 is about 277.7255283178.

The spelling of 21421378 in words is "twenty-one million, four hundred twenty-one thousand, three hundred seventy-eight".