21442777 has 2 divisors, whose sum is σ = 21442778. Its totient is φ = 21442776.

The previous prime is 21442753. The next prime is 21442819. The reversal of 21442777 is 77724412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18974736 + 2468041 = 4356^2 + 1571^2 .

It is a cyclic number.

It is not a de Polignac number, because 21442777 - 2⁷ = 21442649 is a prime.

It is not a weakly prime, because it can be changed into another prime (21442717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721388 + 10721389.

It is an arithmetic number, because the mean of its divisors is an integer number (10721389).

Almost surely, 2^21442777 is an apocalyptic number.

It is an amenable number.

21442777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21442777 is an equidigital number, since it uses as much as digits as its factorization.

21442777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21952, while the sum is 34.

The square root of 21442777 is about 4630.6346217338. The cubic root of 21442777 is about 277.8179760077.

The spelling of 21442777 in words is "twenty-one million, four hundred forty-two thousand, seven hundred seventy-seven".