21378547 has 2 divisors, whose sum is σ = 21378548. Its totient is φ = 21378546.

The previous prime is 21378541. The next prime is 21378587. The reversal of 21378547 is 74587312.

21378547 is nontrivially palindromic in base 12.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21378547 - 2⁷ = 21378419 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21378541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10689273 + 10689274.

It is an arithmetic number, because the mean of its divisors is an integer number (10689274).

Almost surely, 2^21378547 is an apocalyptic number.

21378547 is a deficient number, since it is larger than the sum of its proper divisors (1).

21378547 is an equidigital number, since it uses as much as digits as its factorization.

21378547 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47040, while the sum is 37.

The square root of 21378547 is about 4623.6940859014. The cubic root of 21378547 is about 277.5403052675.

The spelling of 21378547 in words is "twenty-one million, three hundred seventy-eight thousand, five hundred forty-seven".