21401951 has 2 divisors, whose sum is σ = 21401952. Its totient is φ = 21401950.

The previous prime is 21401927. The next prime is 21401953. The reversal of 21401951 is 15910412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21401951 is a prime.

Together with 21401953, 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 (21401953) 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, 10700975 + 10700976.

It is an arithmetic number, because the mean of its divisors is an integer number (10700976).

Almost surely, 2^21401951 is an apocalyptic number.

21401951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21401951 is an equidigital number, since it uses as much as digits as its factorization.

21401951 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 21401951 is about 4626.2242703959. The cubic root of 21401951 is about 277.6415467040.

The spelling of 21401951 in words is "twenty-one million, four hundred one thousand, nine hundred fifty-one".