21577973 has 2 divisors, whose sum is σ = 21577974. Its totient is φ = 21577972.

The previous prime is 21577951. The next prime is 21577987. The reversal of 21577973 is 37977512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20133169 + 1444804 = 4487^2 + 1202^2 .

It is a cyclic number.

It is not a de Polignac number, because 21577973 - 2²² = 17383669 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21577973.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21577273) 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, 10788986 + 10788987.

It is an arithmetic number, because the mean of its divisors is an integer number (10788987).

Almost surely, 2^21577973 is an apocalyptic number.

It is an amenable number.

21577973 is a deficient number, since it is larger than the sum of its proper divisors (1).

21577973 is an equidigital number, since it uses as much as digits as its factorization.

21577973 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 92610, while the sum is 41.

The square root of 21577973 is about 4645.2096831037. The cubic root of 21577973 is about 278.4006308957.

The spelling of 21577973 in words is "twenty-one million, five hundred seventy-seven thousand, nine hundred seventy-three".