1861216457 has 4 divisors (see below), whose sum is σ = 1970699796. Its totient is φ = 1751733120.

The previous prime is 1861216453. The next prime is 1861216463. The reversal of 1861216457 is 7546121681.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 612018121 + 1249198336 = 24739^2 + 35344^2 .

It is a cyclic number.

It is not a de Polignac number, because 1861216457 - 2² = 1861216453 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1861216451) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54741644 + ... + 54741677.

It is an arithmetic number, because the mean of its divisors is an integer number (492674949).

Almost surely, 2^1861216457 is an apocalyptic number.

1861216457 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1861216457 is a deficient number, since it is larger than the sum of its proper divisors (109483339).

1861216457 is a wasteful number, since it uses less digits than its factorization.

1861216457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109483338.

The product of its digits is 80640, while the sum is 41.

The square root of 1861216457 is about 43141.8179612311. The cubic root of 1861216457 is about 1230.0769901353.

The spelling of 1861216457 in words is "one billion, eight hundred sixty-one million, two hundred sixteen thousand, four hundred fifty-seven".