721345105 has 64 divisors (see below), whose sum is σ = 1023865920. Its totient is φ = 483065856.

The previous prime is 721345099. The next prime is 721345109. The reversal of 721345105 is 501543127.

It is a happy number.

It can be written as a sum of positive squares in 32 ways, for example, as 520159249 + 201185856 = 22807^2 + 14184^2 .

It is not a de Polignac number, because 721345105 - 2¹¹ = 721343057 is a prime.

It is a super-2 number, since 2×721345105² = 1040677521014922050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (721345109) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6383529 + ... + 6383641.

It is an arithmetic number, because the mean of its divisors is an integer number (15997905).

Almost surely, 2^721345105 is an apocalyptic number.

It is an amenable number.

721345105 is a deficient number, since it is larger than the sum of its proper divisors (302520815).

721345105 is a wasteful number, since it uses less digits than its factorization.

721345105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310.

The product of its (nonzero) digits is 4200, while the sum is 28.

The square root of 721345105 is about 26857.8685863194. The cubic root of 721345105 is about 896.8387465344.

The spelling of 721345105 in words is "seven hundred twenty-one million, three hundred forty-five thousand, one hundred five".