1621746643 has 4 divisors (see below), whose sum is σ = 1769178168. Its totient is φ = 1474315120.

The previous prime is 1621746563. The next prime is 1621746647. The reversal of 1621746643 is 3466471261.

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

It is a cyclic number.

It is not a de Polignac number, because 1621746643 - 2¹³ = 1621738451 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 1621746596 and 1621746605.

It is not an unprimeable number, because it can be changed into a prime (1621746647) 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, 73715746 + ... + 73715767.

It is an arithmetic number, because the mean of its divisors is an integer number (442294542).

Almost surely, 2^1621746643 is an apocalyptic number.

1621746643 is a deficient number, since it is larger than the sum of its proper divisors (147431525).

1621746643 is a wasteful number, since it uses less digits than its factorization.

1621746643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147431524.

The product of its digits is 145152, while the sum is 40.

The square root of 1621746643 is about 40270.9155967430. The cubic root of 1621746643 is about 1174.8822318665.

The spelling of 1621746643 in words is "one billion, six hundred twenty-one million, seven hundred forty-six thousand, six hundred forty-three".