1645513951 has 4 divisors (see below), whose sum is σ = 1668055312. Its totient is φ = 1622972592.

The previous prime is 1645513931. The next prime is 1645513973. The reversal of 1645513951 is 1593155461.

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 1645513951 - 2⁷ = 1645513823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645513901) 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, 11270571 + ... + 11270716.

It is an arithmetic number, because the mean of its divisors is an integer number (417013828).

Almost surely, 2^1645513951 is an apocalyptic number.

1645513951 is a deficient number, since it is larger than the sum of its proper divisors (22541361).

1645513951 is an equidigital number, since it uses as much as digits as its factorization.

1645513951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22541360.

The product of its digits is 81000, while the sum is 40.

The square root of 1645513951 is about 40564.9349931687. The cubic root of 1645513951 is about 1180.5938672578.

The spelling of 1645513951 in words is "one billion, six hundred forty-five million, five hundred thirteen thousand, nine hundred fifty-one".