1620729856 has 84 divisors (see below), whose sum is σ = 3349406052. Its totient is φ = 784121856.

The previous prime is 1620729839. The next prime is 1620729889. The reversal of 1620729856 is 6589270261.

It is a super-2 number, since 2×1620729856² = 5253530532259561472, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15146955 + ... + 15147061.

Almost surely, 2^1620729856 is an apocalyptic number.

1620729856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1620729856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1674703026).

1620729856 is an abundant number, since it is smaller than the sum of its proper divisors (1728676196).

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

1620729856 is an frugal number, since it uses more digits than its factorization.

1620729856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 46.

The square root of 1620729856 is about 40258.2892830781. The cubic root of 1620729856 is about 1174.6366417734.

The spelling of 1620729856 in words is "one billion, six hundred twenty million, seven hundred twenty-nine thousand, eight hundred fifty-six".