971621909 has 2 divisors, whose sum is σ = 971621910. Its totient is φ = 971621908.

The previous prime is 971621899. The next prime is 971621921. The reversal of 971621909 is 909126179.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 925680625 + 45941284 = 30425^2 + 6778^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-971621909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 971621909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (971621999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 485810954 + 485810955.

It is an arithmetic number, because the mean of its divisors is an integer number (485810955).

Almost surely, 2^971621909 is an apocalyptic number.

It is an amenable number.

971621909 is a deficient number, since it is larger than the sum of its proper divisors (1).

971621909 is an equidigital number, since it uses as much as digits as its factorization.

971621909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 44.

The square root of 971621909 is about 31170.8503092232. The cubic root of 971621909 is about 990.4497188162.

The spelling of 971621909 in words is "nine hundred seventy-one million, six hundred twenty-one thousand, nine hundred nine".