21440351 has 2 divisors, whose sum is σ = 21440352. Its totient is φ = 21440350.

The previous prime is 21440317. The next prime is 21440357. The reversal of 21440351 is 15304412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21440351 is a prime.

It is equal to p_1356032 and since 21440351 and 1356032 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21440357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720175 + 10720176.

It is an arithmetic number, because the mean of its divisors is an integer number (10720176).

Almost surely, 2^21440351 is an apocalyptic number.

21440351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440351 is an equidigital number, since it uses as much as digits as its factorization.

21440351 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21440351 is about 4630.3726631881. The cubic root of 21440351 is about 277.8074983252.

Adding to 21440351 its reverse (15304412), we get a palindrome (36744763).

The spelling of 21440351 in words is "twenty-one million, four hundred forty thousand, three hundred fifty-one".