21471947999 has 2 divisors, whose sum is σ = 21471948000. Its totient is φ = 21471947998.

The previous prime is 21471947989. The next prime is 21471948053. The reversal of 21471947999 is 99974917412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21471947999 - 2¹² = 21471943903 is a prime.

It is a super-2 number, since 2×21471947999² (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 (21471947909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10735973999 + 10735974000.

It is an arithmetic number, because the mean of its divisors is an integer number (10735974000).

Almost surely, 2^21471947999 is an apocalyptic number.

21471947999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21471947999 is an equidigital number, since it uses as much as digits as its factorization.

21471947999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10287648, while the sum is 62.

The spelling of 21471947999 in words is "twenty-one billion, four hundred seventy-one million, nine hundred forty-seven thousand, nine hundred ninety-nine".