21193387 has 2 divisors, whose sum is σ = 21193388. Its totient is φ = 21193386.

The previous prime is 21193369. The next prime is 21193391. The reversal of 21193387 is 78339112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21193387 - 2⁷ = 21193259 is a prime.

It is not a weakly prime, because it can be changed into another prime (21193307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10596693 + 10596694.

It is an arithmetic number, because the mean of its divisors is an integer number (10596694).

Almost surely, 2^21193387 is an apocalyptic number.

21193387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21193387 is an equidigital number, since it uses as much as digits as its factorization.

21193387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 34.

The square root of 21193387 is about 4603.6275913675. The cubic root of 21193387 is about 276.7367202164.

The spelling of 21193387 in words is "twenty-one million, one hundred ninety-three thousand, three hundred eighty-seven".