165721862544 has 80 divisors (see below), whose sum is σ = 491040678528. Its totient is φ = 47178141696.

The previous prime is 165721862539. The next prime is 165721862549. The reversal of 165721862544 is 445268127561.

It is an interprime number because it is at equal distance from previous prime (165721862539) and next prime (165721862549).

It is not an unprimeable number, because it can be changed into a prime (165721862549) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 797217 + ... + 983360.

Almost surely, 2^165721862544 is an apocalyptic number.

165721862544 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

165721862544 is an abundant number, since it is smaller than the sum of its proper divisors (325318815984).

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

165721862544 is a wasteful number, since it uses less digits than its factorization.

165721862544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780872 (or 1780866 counting only the distinct ones).

The product of its digits is 3225600, while the sum is 51.

The spelling of 165721862544 in words is "one hundred sixty-five billion, seven hundred twenty-one million, eight hundred sixty-two thousand, five hundred forty-four".