1645356543521 has 8 divisors (see below), whose sum is σ = 1666286371680. Its totient is φ = 1624507682688.

The previous prime is 1645356543431. The next prime is 1645356543533. The reversal of 1645356543521 is 1253456535461.

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 1645356543521 - 2²² = 1645352349217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1645356543521.

It is not an unprimeable number, because it can be changed into a prime (1645356543541) 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, 20200931 + ... + 20282216.

It is an arithmetic number, because the mean of its divisors is an integer number (208285796460).

Almost surely, 2^{1645356543521} is an apocalyptic number.

It is an amenable number.

1645356543521 is a deficient number, since it is larger than the sum of its proper divisors (20929828159).

1645356543521 is an equidigital number, since it uses as much as digits as its factorization.

1645356543521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40483663.

The product of its digits is 6480000, while the sum is 50.

The spelling of 1645356543521 in words is "one trillion, six hundred forty-five billion, three hundred fifty-six million, five hundred forty-three thousand, five hundred twenty-one".