1231581397 has 8 divisors (see below), whose sum is σ = 1243218240. Its totient is φ = 1219997760.

The previous prime is 1231581343. The next prime is 1231581419. The reversal of 1231581397 is 7931851321.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1231581397 - 2¹⁹ = 1231057109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231581497) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33997 + ... + 60157.

It is an arithmetic number, because the mean of its divisors is an integer number (155402280).

Almost surely, 2^1231581397 is an apocalyptic number.

It is an amenable number.

1231581397 is a deficient number, since it is larger than the sum of its proper divisors (11636843).

1231581397 is a wasteful number, since it uses less digits than its factorization.

1231581397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26603.

The product of its digits is 45360, while the sum is 40.

The square root of 1231581397 is about 35093.8940130616. The cubic root of 1231581397 is about 1071.9002529921.

The spelling of 1231581397 in words is "one billion, two hundred thirty-one million, five hundred eighty-one thousand, three hundred ninety-seven".