21147397919 has 2 divisors, whose sum is σ = 21147397920. Its totient is φ = 21147397918.

The previous prime is 21147397897. The next prime is 21147397927. The reversal of 21147397919 is 91979374112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21147397919 - 2¹² = 21147393823 is a prime.

It is a super-2 number, since 2×21147397919² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21147397949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10573698959 + 10573698960.

It is an arithmetic number, because the mean of its divisors is an integer number (10573698960).

Almost surely, 2^21147397919 is an apocalyptic number.

21147397919 is a deficient number, since it is larger than the sum of its proper divisors (1).

21147397919 is an equidigital number, since it uses as much as digits as its factorization.

21147397919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 857304, while the sum is 53.

The spelling of 21147397919 in words is "twenty-one billion, one hundred forty-seven million, three hundred ninety-seven thousand, nine hundred nineteen".