21420499 has 2 divisors, whose sum is σ = 21420500. Its totient is φ = 21420498.

The previous prime is 21420479. The next prime is 21420541. The reversal of 21420499 is 99402412.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21420499 - 2²¹ = 19323347 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21420499.

It is not a weakly prime, because it can be changed into another prime (21420439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710249 + 10710250.

It is an arithmetic number, because the mean of its divisors is an integer number (10710250).

Almost surely, 2^21420499 is an apocalyptic number.

21420499 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420499 is an equidigital number, since it uses as much as digits as its factorization.

21420499 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21420499 is about 4628.2284947915. The cubic root of 21420499 is about 277.7217295569.

The spelling of 21420499 in words is "twenty-one million, four hundred twenty thousand, four hundred ninety-nine".