1645953978 has 16 divisors (see below), whose sum is σ = 3292508736. Its totient is φ = 548551200.

The previous prime is 1645953977. The next prime is 1645953989. The reversal of 1645953978 is 8793595461.

It is not an unprimeable number, because it can be changed into a prime (1645953977) 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, 15678 + ... + 59478.

It is an arithmetic number, because the mean of its divisors is an integer number (205781796).

Almost surely, 2^1645953978 is an apocalyptic number.

1645953978 is an abundant number, since it is smaller than the sum of its proper divisors (1646554758).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1645953978 is a wasteful number, since it uses less digits than its factorization.

1645953978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50069.

The product of its digits is 8164800, while the sum is 57.

The square root of 1645953978 is about 40570.3583666696. The cubic root of 1645953978 is about 1180.6990921083.

The spelling of 1645953978 in words is "one billion, six hundred forty-five million, nine hundred fifty-three thousand, nine hundred seventy-eight".