21956801 has 2 divisors, whose sum is σ = 21956802. Its totient is φ = 21956800.

The previous prime is 21956777. The next prime is 21956807. The reversal of 21956801 is 10865912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14250625 + 7706176 = 3775^2 + 2776^2 .

It is a cyclic number.

It is not a de Polignac number, because 21956801 - 2¹⁸ = 21694657 is a prime.

It is a super-2 number, since 2×21956801² = 964202220307202, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_1386716 and since 21956801 and 1386716 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21956807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978400 + 10978401.

It is an arithmetic number, because the mean of its divisors is an integer number (10978401).

Almost surely, 2^21956801 is an apocalyptic number.

It is an amenable number.

21956801 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956801 is an equidigital number, since it uses as much as digits as its factorization.

21956801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 21956801 is about 4685.8084681301. The cubic root of 21956801 is about 280.0204109271.

The spelling of 21956801 in words is "twenty-one million, nine hundred fifty-six thousand, eight hundred one".