101397721 has 2 divisors, whose sum is σ = 101397722. Its totient is φ = 101397720.

The previous prime is 101397719. The next prime is 101397739. The reversal of 101397721 is 127793101.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74149321 + 27248400 = 8611^2 + 5220^2 .

It is an emirp because it is prime and its reverse (127793101) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 101397721 - 2¹ = 101397719 is a prime.

Together with 101397719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (101397701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50698860 + 50698861.

It is an arithmetic number, because the mean of its divisors is an integer number (50698861).

Almost surely, 2^101397721 is an apocalyptic number.

It is an amenable number.

101397721 is a deficient number, since it is larger than the sum of its proper divisors (1).

101397721 is an equidigital number, since it uses as much as digits as its factorization.

101397721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2646, while the sum is 31.

The square root of 101397721 is about 10069.6435388747. The cubic root of 101397721 is about 466.3114341396.

The spelling of 101397721 in words is "one hundred one million, three hundred ninety-seven thousand, seven hundred twenty-one".