1644426403 has 4 divisors (see below), whose sum is σ = 1697472448. Its totient is φ = 1591380360.

The previous prime is 1644426367. The next prime is 1644426419. The reversal of 1644426403 is 3046244461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3046244461 = 13 ⋅234326497.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1644426403 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1644426503) 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, 26522976 + ... + 26523037.

It is an arithmetic number, because the mean of its divisors is an integer number (424368112).

Almost surely, 2^1644426403 is an apocalyptic number.

1644426403 is a deficient number, since it is larger than the sum of its proper divisors (53046045).

1644426403 is an equidigital number, since it uses as much as digits as its factorization.

1644426403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53046044.

The product of its (nonzero) digits is 55296, while the sum is 34.

The square root of 1644426403 is about 40551.5277517383. The cubic root of 1644426403 is about 1180.3337184526. Note that the first 3 decimals are identical.

The spelling of 1644426403 in words is "one billion, six hundred forty-four million, four hundred twenty-six thousand, four hundred three".