1387721 has 2 divisors, whose sum is σ = 1387722. Its totient is φ = 1387720.

The previous prime is 1387717. The next prime is 1387733. The reversal of 1387721 is 1277831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 978121 + 409600 = 989^2 + 640^2 .

It is a cyclic number.

It is not a de Polignac number, because 1387721 - 2² = 1387717 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1387781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 693860 + 693861.

It is an arithmetic number, because the mean of its divisors is an integer number (693861).

2^1387721 is an apocalyptic number.

It is an amenable number.

1387721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1387721 is an equidigital number, since it uses as much as digits as its factorization.

1387721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2352, while the sum is 29.

The square root of 1387721 is about 1178.0157044794. The cubic root of 1387721 is about 111.5408766452.

The spelling of 1387721 in words is "one million, three hundred eighty-seven thousand, seven hundred twenty-one".