721420340 has 24 divisors (see below), whose sum is σ = 1520625960. Its totient is φ = 287493248.

The previous prime is 721420333. The next prime is 721420397. The reversal of 721420340 is 43024127.

It can be written as a sum of positive squares in 4 ways, for example, as 40627876 + 680792464 = 6374^2 + 26092^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61667 + ... + 72426.

It is an arithmetic number, because the mean of its divisors is an integer number (63359415).

Almost surely, 2^721420340 is an apocalyptic number.

It is an amenable number.

721420340 is an abundant number, since it is smaller than the sum of its proper divisors (799205620).

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

721420340 is a wasteful number, since it uses less digits than its factorization.

721420340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134371 (or 134369 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 721420340 is about 26859.2691635495. The cubic root of 721420340 is about 896.8699250078.

Adding to 721420340 its reverse (43024127), we get a palindrome (764444467).

The spelling of 721420340 in words is "seven hundred twenty-one million, four hundred twenty thousand, three hundred forty".