21956461 has 2 divisors, whose sum is σ = 21956462. Its totient is φ = 21956460.

The previous prime is 21956423. The next prime is 21956471. The reversal of 21956461 is 16465912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12033961 + 9922500 = 3469^2 + 3150^2 .

It is a cyclic number.

It is not a de Polignac number, because 21956461 - 2²¹ = 19859309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21956471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978230 + 10978231.

It is an arithmetic number, because the mean of its divisors is an integer number (10978231).

Almost surely, 2^21956461 is an apocalyptic number.

It is an amenable number.

21956461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956461 is an equidigital number, since it uses as much as digits as its factorization.

21956461 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 34.

The square root of 21956461 is about 4685.7721882311. The cubic root of 21956461 is about 280.0189655521.

The spelling of 21956461 in words is "twenty-one million, nine hundred fifty-six thousand, four hundred sixty-one".