721861632 has 154 divisors (see below), whose sum is σ = 2165775128. Its totient is φ = 240371712.

The previous prime is 721861627. The next prime is 721861639. The reversal of 721861632 is 236168127.

721861632 is a `hidden beast` number, since 7 + 2 + 1 + 8 + 616 + 32 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721861639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 746013 + ... + 746979.

Almost surely, 2^721861632 is an apocalyptic number.

721861632 is a gapful number since it is divisible by the number (72) 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 721861632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1082887564).

721861632 is an abundant number, since it is smaller than the sum of its proper divisors (1443913496).

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

721861632 is an frugal number, since it uses more digits than its factorization.

721861632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1005 (or 972 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 721861632 is about 26867.4827998456. The cubic root of 721861632 is about 897.0527591701.

The spelling of 721861632 in words is "seven hundred twenty-one million, eight hundred sixty-one thousand, six hundred thirty-two".