21425777 has 2 divisors, whose sum is σ = 21425778. Its totient is φ = 21425776.

The previous prime is 21425773. The next prime is 21425779. The reversal of 21425777 is 77752412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20511841 + 913936 = 4529^2 + 956^2 .

It is a cyclic number.

It is not a de Polignac number, because 21425777 - 2² = 21425773 is a prime.

Together with 21425779, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21425773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712888 + 10712889.

It is an arithmetic number, because the mean of its divisors is an integer number (10712889).

Almost surely, 2^21425777 is an apocalyptic number.

It is an amenable number.

21425777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21425777 is an equidigital number, since it uses as much as digits as its factorization.

21425777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27440, while the sum is 35.

The square root of 21425777 is about 4628.7986562390. The cubic root of 21425777 is about 277.7445378477.

The spelling of 21425777 in words is "twenty-one million, four hundred twenty-five thousand, seven hundred seventy-seven".