27801721 has 2 divisors, whose sum is σ = 27801722. Its totient is φ = 27801720.

The previous prime is 27801713. The next prime is 27801757. The reversal of 27801721 is 12710872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26409321 + 1392400 = 5139^2 + 1180^2 .

It is a cyclic number.

It is not a de Polignac number, because 27801721 - 2³ = 27801713 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 27801721.

It is not a weakly prime, because it can be changed into another prime (27801701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13900860 + 13900861.

It is an arithmetic number, because the mean of its divisors is an integer number (13900861).

Almost surely, 2^27801721 is an apocalyptic number.

It is an amenable number.

27801721 is a deficient number, since it is larger than the sum of its proper divisors (1).

27801721 is an equidigital number, since it uses as much as digits as its factorization.

27801721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 27801721 is about 5272.7337311873. The cubic root of 27801721 is about 302.9404225938.

The spelling of 27801721 in words is "twenty-seven million, eight hundred one thousand, seven hundred twenty-one".