21955361 has 4 divisors (see below), whose sum is σ = 21964800. Its totient is φ = 21945924.

The previous prime is 21955343. The next prime is 21955399. The reversal of 21955361 is 16355912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21955361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21955861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1520 + ... + 6798.

It is an arithmetic number, because the mean of its divisors is an integer number (5491200).

Almost surely, 2^21955361 is an apocalyptic number.

It is an amenable number.

21955361 is a deficient number, since it is larger than the sum of its proper divisors (9439).

21955361 is an equidigital number, since it uses as much as digits as its factorization.

21955361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9438.

The product of its digits is 8100, while the sum is 32.

The square root of 21955361 is about 4685.6548101626. The cubic root of 21955361 is about 280.0142892368.

The spelling of 21955361 in words is "twenty-one million, nine hundred fifty-five thousand, three hundred sixty-one".