721690501 has 4 divisors (see below), whose sum is σ = 824789152. Its totient is φ = 618591852.

The previous prime is 721690427. The next prime is 721690553. The reversal of 721690501 is 105096127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721690501 - 2⁷ = 721690373 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721090501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51549315 + ... + 51549328.

It is an arithmetic number, because the mean of its divisors is an integer number (206197288).

Almost surely, 2^721690501 is an apocalyptic number.

It is an amenable number.

721690501 is a deficient number, since it is larger than the sum of its proper divisors (103098651).

721690501 is a wasteful number, since it uses less digits than its factorization.

721690501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103098650.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 721690501 is about 26864.2978877171. The cubic root of 721690501 is about 896.9818657738.

The spelling of 721690501 in words is "seven hundred twenty-one million, six hundred ninety thousand, five hundred one".