1645023670621 has 4 divisors (see below), whose sum is σ = 1648770877600. Its totient is φ = 1641276463644.

The previous prime is 1645023670603. The next prime is 1645023670639. The reversal of 1645023670621 is 1260763205461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (1645023670603) and next prime (1645023670639).

It is a cyclic number.

It is not a de Polignac number, because 1645023670621 - 2¹¹ = 1645023668573 is a prime.

It is a super-2 number, since 2×1645023670621² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645023670721) 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, 1873602831 + ... + 1873603708.

It is an arithmetic number, because the mean of its divisors is an integer number (412192719400).

Almost surely, 2^{1645023670621} is an apocalyptic number.

It is an amenable number.

1645023670621 is a deficient number, since it is larger than the sum of its proper divisors (3747206979).

1645023670621 is an equidigital number, since it uses as much as digits as its factorization.

1645023670621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3747206978.

The product of its (nonzero) digits is 362880, while the sum is 43.

The spelling of 1645023670621 in words is "one trillion, six hundred forty-five billion, twenty-three million, six hundred seventy thousand, six hundred twenty-one".