1645123440 has 40 divisors (see below), whose sum is σ = 5099883408. Its totient is φ = 438699520.

The previous prime is 1645123433. The next prime is 1645123523. The reversal of 1645123440 is 443215461.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×1645123440² = 5412862265674867200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1645123398 and 1645123407.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3427101 + ... + 3427580.

Almost surely, 2^1645123440 is an apocalyptic number.

1645123440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1645123440 is an abundant number, since it is smaller than the sum of its proper divisors (3454759968).

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

1645123440 is a wasteful number, since it uses less digits than its factorization.

1645123440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6854697 (or 6854691 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 1645123440 is about 40560.1213015938. The cubic root of 1645123440 is about 1180.5004675904.

The spelling of 1645123440 in words is "one billion, six hundred forty-five million, one hundred twenty-three thousand, four hundred forty".