1645398381 has 8 divisors (see below), whose sum is σ = 2393306784. Its totient is φ = 997211120.

The previous prime is 1645398367. The next prime is 1645398413. The reversal of 1645398381 is 1838935461.

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 1645398381 - 2¹⁰ = 1645397357 is a prime.

It is a super-2 number, since 2×1645398381² = 5414671664394842322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1645398381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645398331) 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, 24930246 + ... + 24930311.

It is an arithmetic number, because the mean of its divisors is an integer number (299163348).

Almost surely, 2^1645398381 is an apocalyptic number.

1645398381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1645398381 is a deficient number, since it is larger than the sum of its proper divisors (747908403).

1645398381 is a wasteful number, since it uses less digits than its factorization.

1645398381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49860571.

The product of its digits is 622080, while the sum is 48.

The square root of 1645398381 is about 40563.5104619903. The cubic root of 1645398381 is about 1180.5662275797.

The spelling of 1645398381 in words is "one billion, six hundred forty-five million, three hundred ninety-eight thousand, three hundred eighty-one".