1645731623 has 2 divisors, whose sum is σ = 1645731624. Its totient is φ = 1645731622.

The previous prime is 1645731599. The next prime is 1645731667. The reversal of 1645731623 is 3261375461.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1645731623 - 2¹⁸ = 1645469479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1645031623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822865811 + 822865812.

It is an arithmetic number, because the mean of its divisors is an integer number (822865812).

Almost surely, 2^1645731623 is an apocalyptic number.

1645731623 is a deficient number, since it is larger than the sum of its proper divisors (1).

1645731623 is an equidigital number, since it uses as much as digits as its factorization.

1645731623 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 38.

The square root of 1645731623 is about 40567.6179113342. The cubic root of 1645731623 is about 1180.6459220981.

The spelling of 1645731623 in words is "one billion, six hundred forty-five million, seven hundred thirty-one thousand, six hundred twenty-three".