21417423991 has 2 divisors, whose sum is σ = 21417423992. Its totient is φ = 21417423990.

The previous prime is 21417423983. The next prime is 21417424081. The reversal of 21417423991 is 19932471412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21417423991 - 2³ = 21417423983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21417426991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708711995 + 10708711996.

It is an arithmetic number, because the mean of its divisors is an integer number (10708711996).

Almost surely, 2^21417423991 is an apocalyptic number.

21417423991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21417423991 is an equidigital number, since it uses as much as digits as its factorization.

21417423991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 43.

The spelling of 21417423991 in words is "twenty-one billion, four hundred seventeen million, four hundred twenty-three thousand, nine hundred ninety-one".