1645695651 has 4 divisors (see below), whose sum is σ = 2194260872. Its totient is φ = 1097130432.

The previous prime is 1645695641. The next prime is 1645695661. The reversal of 1645695651 is 1565965461.

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

It is an interprime number because it is at equal distance from previous prime (1645695641) and next prime (1645695661).

It is not a de Polignac number, because 1645695651 - 2⁵ = 1645695619 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 1645695651.

It is not an unprimeable number, because it can be changed into a prime (1645695641) 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, 274282606 + ... + 274282611.

It is an arithmetic number, because the mean of its divisors is an integer number (548565218).

Almost surely, 2^1645695651 is an apocalyptic number.

1645695651 is a deficient number, since it is larger than the sum of its proper divisors (548565221).

1645695651 is an equidigital number, since it uses as much as digits as its factorization.

1645695651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548565220.

The product of its digits is 972000, while the sum is 48.

The square root of 1645695651 is about 40567.1745503677. The cubic root of 1645695651 is about 1180.6373199453.

The spelling of 1645695651 in words is "one billion, six hundred forty-five million, six hundred ninety-five thousand, six hundred fifty-one".