21415789 has 2 divisors, whose sum is σ = 21415790. Its totient is φ = 21415788.

The previous prime is 21415787. The next prime is 21415811. The reversal of 21415789 is 98751412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21206025 + 209764 = 4605^2 + 458^2 .

It is a cyclic number.

It is not a de Polignac number, because 21415789 - 2¹ = 21415787 is a prime.

Together with 21415787, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21415781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10707894 + 10707895.

It is an arithmetic number, because the mean of its divisors is an integer number (10707895).

Almost surely, 2^21415789 is an apocalyptic number.

It is an amenable number.

21415789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21415789 is an equidigital number, since it uses as much as digits as its factorization.

21415789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 37.

The square root of 21415789 is about 4627.7196328213. The cubic root of 21415789 is about 277.7013726512.

The spelling of 21415789 in words is "twenty-one million, four hundred fifteen thousand, seven hundred eighty-nine".