721898749 has 64 divisors (see below), whose sum is σ = 943810560. Its totient is φ = 542142720.

The previous prime is 721898729. The next prime is 721898773. The reversal of 721898749 is 947898127.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 721898749 - 2⁹ = 721898237 is a prime.

It is a super-2 number, since 2×721898749² = 1042275607615530002, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 721898749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721898729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4322664 + ... + 4322830.

It is an arithmetic number, because the mean of its divisors is an integer number (14747040).

Almost surely, 2^721898749 is an apocalyptic number.

721898749 is the 14362-nd nonagonal number.

It is an amenable number.

721898749 is a deficient number, since it is larger than the sum of its proper divisors (221911811).

721898749 is a wasteful number, since it uses less digits than its factorization.

721898749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290.

The product of its digits is 2032128, while the sum is 55.

The square root of 721898749 is about 26868.1735330111. The cubic root of 721898749 is about 897.0681339249.

The spelling of 721898749 in words is "seven hundred twenty-one million, eight hundred ninety-eight thousand, seven hundred forty-nine".