21194387 has 2 divisors, whose sum is σ = 21194388. Its totient is φ = 21194386.

The previous prime is 21194353. The next prime is 21194441. The reversal of 21194387 is 78349112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21194387 - 2⁶ = 21194323 is a prime.

It is not a weakly prime, because it can be changed into another prime (21194587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10597193 + 10597194.

It is an arithmetic number, because the mean of its divisors is an integer number (10597194).

Almost surely, 2^21194387 is an apocalyptic number.

21194387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21194387 is an equidigital number, since it uses as much as digits as its factorization.

21194387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 21194387 is about 4603.7362000879. The cubic root of 21194387 is about 276.7410727119.

The spelling of 21194387 in words is "twenty-one million, one hundred ninety-four thousand, three hundred eighty-seven".