1645679520 has 72 divisors (see below), whose sum is σ = 5615886276. Its totient is φ = 438847488.

The previous prime is 1645679489. The next prime is 1645679537. The reversal of 1645679520 is 259765461.

1645679520 is a `hidden beast` number, since 1 + 6 + 4 + 56 + 79 + 520 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1521936144 + 123743376 = 39012^2 + 11124^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×1645679520² = 5416522165094860800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 569977 + ... + 572856.

Almost surely, 2^1645679520 is an apocalyptic number.

1645679520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1645679520 is an abundant number, since it is smaller than the sum of its proper divisors (3970206756).

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

1645679520 is a wasteful number, since it uses less digits than its factorization.

1645679520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1142854 (or 1142843 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 45.

The square root of 1645679520 is about 40566.9757314986. The cubic root of 1645679520 is about 1180.6334624231.

The spelling of 1645679520 in words is "one billion, six hundred forty-five million, six hundred seventy-nine thousand, five hundred twenty".