721287840 has 384 divisors, whose sum is σ = 2861913600. Its totient is φ = 151732224.

The previous prime is 721287821. The next prime is 721287857. The reversal of 721287840 is 48782127.

It is a super-2 number, since 2×721287840² = 1040512296263731200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2140152 + ... + 2140488.

It is an arithmetic number, because the mean of its divisors is an integer number (7452900).

Almost surely, 2^721287840 is an apocalyptic number.

721287840 is a gapful number since it is divisible by the number (70) 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 721287840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1430956800).

721287840 is an abundant number, since it is smaller than the sum of its proper divisors (2140625760).

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

721287840 is a wasteful number, since it uses less digits than its factorization.

721287840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389 (or 367 counting only the distinct ones).

The product of its (nonzero) digits is 50176, while the sum is 39.

The square root of 721287840 is about 26856.8024902444. The cubic root of 721287840 is about 896.8150136362.

The spelling of 721287840 in words is "seven hundred twenty-one million, two hundred eighty-seven thousand, eight hundred forty".