21440051 has 2 divisors, whose sum is σ = 21440052. Its totient is φ = 21440050.

The previous prime is 21440039. The next prime is 21440059. The reversal of 21440051 is 15004412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21440051 - 2⁶ = 21439987 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21440059) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10720025 + 10720026.

It is an arithmetic number, because the mean of its divisors is an integer number (10720026).

Almost surely, 2^21440051 is an apocalyptic number.

21440051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21440051 is an equidigital number, since it uses as much as digits as its factorization.

21440051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21440051 is about 4630.3402682740. The cubic root of 21440051 is about 277.8062025964.

Adding to 21440051 its reverse (15004412), we get a palindrome (36444463).

The spelling of 21440051 in words is "twenty-one million, four hundred forty thousand, fifty-one".