21754991 has 2 divisors, whose sum is σ = 21754992. Its totient is φ = 21754990.

The previous prime is 21754961. The next prime is 21755003. The reversal of 21754991 is 19945712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21754991 - 2¹⁰ = 21753967 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21754961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10877495 + 10877496.

It is an arithmetic number, because the mean of its divisors is an integer number (10877496).

Almost surely, 2^21754991 is an apocalyptic number.

21754991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21754991 is an equidigital number, since it uses as much as digits as its factorization.

21754991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 38.

The square root of 21754991 is about 4664.2245872170. The cubic root of 21754991 is about 279.1598583721.

The spelling of 21754991 in words is "twenty-one million, seven hundred fifty-four thousand, nine hundred ninety-one".