1213856397 has 18 divisors (see below), whose sum is σ = 1888807466. Its totient is φ = 746756640.

The previous prime is 1213856387. The next prime is 1213856431. The reversal of 1213856397 is 7936583121.

1213856397 is a `hidden beast` number, since 1 + 2 + 1 + 3 + 8 + 5 + 639 + 7 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 263120841 + 950735556 = 16221^2 + 30834^2 .

It is not a de Polignac number, because 1213856397 - 2⁷ = 1213856269 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1213856317) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 375247 + ... + 378467.

Almost surely, 2^1213856397 is an apocalyptic number.

It is an amenable number.

1213856397 is a deficient number, since it is larger than the sum of its proper divisors (674951069).

1213856397 is an frugal number, since it uses more digits than its factorization.

1213856397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6461 (or 3237 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The square root of 1213856397 is about 34840.4419748085. The cubic root of 1213856397 is about 1066.7330982823.

The spelling of 1213856397 in words is "one billion, two hundred thirteen million, eight hundred fifty-six thousand, three hundred ninety-seven".