1691953397 has 6 divisors (see below), whose sum is σ = 1724482242. Its totient is φ = 1660026992.

The previous prime is 1691953381. The next prime is 1691953411. The reversal of 1691953397 is 7933591961.

It can be written as a sum of positive squares in 3 ways, for example, as 921668881 + 770284516 = 30359^2 + 27754^2 .

It is not a de Polignac number, because 1691953397 - 2⁴ = 1691953381 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (53).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1691953897) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 298358 + ... + 303975.

It is an arithmetic number, because the mean of its divisors is an integer number (287413707).

Almost surely, 2^1691953397 is an apocalyptic number.

It is an amenable number.

1691953397 is a deficient number, since it is larger than the sum of its proper divisors (32528845).

1691953397 is an frugal number, since it uses more digits than its factorization.

1691953397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 602439 (or 602386 counting only the distinct ones).

The product of its digits is 1377810, while the sum is 53.

The square root of 1691953397 is about 41133.3611196557. The cubic root of 1691953397 is about 1191.5971767413.

The spelling of 1691953397 in words is "one billion, six hundred ninety-one million, nine hundred fifty-three thousand, three hundred ninety-seven".