21754961 has 2 divisors, whose sum is σ = 21754962. Its totient is φ = 21754960.

The previous prime is 21754891. The next prime is 21754991. The reversal of 21754961 is 16945712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21022225 + 732736 = 4585^2 + 856^2 .

It is a cyclic number.

It is not a de Polignac number, because 21754961 - 2¹⁰ = 21753937 is a prime.

It is a super-2 number, since 2×21754961² = 946556656223042, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21754991) 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, 10877480 + 10877481.

It is an arithmetic number, because the mean of its divisors is an integer number (10877481).

Almost surely, 2^21754961 is an apocalyptic number.

It is an amenable number.

21754961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21754961 is an equidigital number, since it uses as much as digits as its factorization.

21754961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 35.

The square root of 21754961 is about 4664.2213712473. The cubic root of 21754961 is about 279.1597300521.

Subtracting from 21754961 its reverse (16945712), we obtain a square (4809249 = 2193²).

The spelling of 21754961 in words is "twenty-one million, seven hundred fifty-four thousand, nine hundred sixty-one".