7664721820 has 24 divisors (see below), whose sum is σ = 18395332704. Its totient is φ = 2627904576.

The previous prime is 7664721803. The next prime is 7664721833. The reversal of 7664721820 is 281274667.

It is a super-2 number, since 2×7664721820² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27373867 + ... + 27374146.

It is an arithmetic number, because the mean of its divisors is an integer number (766472196).

Almost surely, 2^7664721820 is an apocalyptic number.

7664721820 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

7664721820 is an abundant number, since it is smaller than the sum of its proper divisors (10730610884).

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

7664721820 is a wasteful number, since it uses less digits than its factorization.

7664721820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54748029 (or 54748027 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 43.

The square root of 7664721820 is about 87548.3970155936. The cubic root of 7664721820 is about 1971.6604842796.

The spelling of 7664721820 in words is "seven billion, six hundred sixty-four million, seven hundred twenty-one thousand, eight hundred twenty".