21327961 has 2 divisors, whose sum is σ = 21327962. Its totient is φ = 21327960.

The previous prime is 21327953. The next prime is 21327973. The reversal of 21327961 is 16972312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20793600 + 534361 = 4560^2 + 731^2 .

It is a cyclic number.

It is not a de Polignac number, because 21327961 - 2³ = 21327953 is a prime.

It is not a weakly prime, because it can be changed into another prime (21327931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10663980 + 10663981.

It is an arithmetic number, because the mean of its divisors is an integer number (10663981).

Almost surely, 2^21327961 is an apocalyptic number.

It is an amenable number.

21327961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21327961 is an equidigital number, since it uses as much as digits as its factorization.

21327961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536, while the sum is 31.

The square root of 21327961 is about 4618.2205447553. The cubic root of 21327961 is about 277.3212267364.

The spelling of 21327961 in words is "twenty-one million, three hundred twenty-seven thousand, nine hundred sixty-one".