21442451 has 2 divisors, whose sum is σ = 21442452. Its totient is φ = 21442450.

The previous prime is 21442439. The next prime is 21442459. The reversal of 21442451 is 15424412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21442451 is a prime.

It is not a weakly prime, because it can be changed into another prime (21442459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10721225 + 10721226.

It is an arithmetic number, because the mean of its divisors is an integer number (10721226).

Almost surely, 2^21442451 is an apocalyptic number.

21442451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21442451 is an equidigital number, since it uses as much as digits as its factorization.

21442451 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1280, while the sum is 23.

The square root of 21442451 is about 4630.5994212413. The cubic root of 21442451 is about 277.8165680881.

Adding to 21442451 its reverse (15424412), we get a palindrome (36866863).

The spelling of 21442451 in words is "twenty-one million, four hundred forty-two thousand, four hundred fifty-one".