21402077 has 2 divisors, whose sum is σ = 21402078. Its totient is φ = 21402076.

The previous prime is 21402053. The next prime is 21402079. The reversal of 21402077 is 77020412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17757796 + 3644281 = 4214^2 + 1909^2 .

It is a cyclic number.

It is not a de Polignac number, because 21402077 - 2⁶ = 21402013 is a prime.

Together with 21402079, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21402079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701038 + 10701039.

It is an arithmetic number, because the mean of its divisors is an integer number (10701039).

Almost surely, 2^21402077 is an apocalyptic number.

It is an amenable number.

21402077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21402077 is an equidigital number, since it uses as much as digits as its factorization.

21402077 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 784, while the sum is 23.

The square root of 21402077 is about 4626.2378883927. The cubic root of 21402077 is about 277.6420915573.

Adding to 21402077 its reverse (77020412), we get a palindrome (98422489).

The spelling of 21402077 in words is "twenty-one million, four hundred two thousand, seventy-seven".