21402401 has 2 divisors, whose sum is σ = 21402402. Its totient is φ = 21402400.

The previous prime is 21402383. The next prime is 21402419. The reversal of 21402401 is 10420412.

It is a balanced prime because it is at equal distance from previous prime (21402383) and next prime (21402419).

It can be written as a sum of positive squares in only one way, i.e., 21381376 + 21025 = 4624^2 + 145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21402401 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21402481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701200 + 10701201.

It is an arithmetic number, because the mean of its divisors is an integer number (10701201).

Almost surely, 2^21402401 is an apocalyptic number.

It is an amenable number.

21402401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21402401 is an equidigital number, since it uses as much as digits as its factorization.

21402401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21402401 is about 4626.2729059147. The cubic root of 21402401 is about 277.6434925986.

Adding to 21402401 its reverse (10420412), we get a palindrome (31822813).

The spelling of 21402401 in words is "twenty-one million, four hundred two thousand, four hundred one".