721011866 has 16 divisors (see below), whose sum is σ = 1152555264. Its totient is φ = 337493904.

The previous prime is 721011853. The next prime is 721011869. The reversal of 721011866 is 668110127.

It is a happy number.

It is a super-2 number, since 2×721011866² = 1039716221825603912, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (721011869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164585 + ... + 168908.

It is an arithmetic number, because the mean of its divisors is an integer number (72034704).

Almost surely, 2^721011866 is an apocalyptic number.

721011866 is a deficient number, since it is larger than the sum of its proper divisors (431543398).

721011866 is a wasteful number, since it uses less digits than its factorization.

721011866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333565.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 721011866 is about 26851.6641197524. The cubic root of 721011866 is about 896.7006213946.

The spelling of 721011866 in words is "seven hundred twenty-one million, eleven thousand, eight hundred sixty-six".