721642554 has 64 divisors (see below), whose sum is σ = 1756598400. Its totient is φ = 218582784.

The previous prime is 721642529. The next prime is 721642567. The reversal of 721642554 is 455246127.

It is a happy number.

721642554 is a `hidden beast` number, since 7 + 2 + 1 + 642 + 5 + 5 + 4 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13069 + ... + 40175.

It is an arithmetic number, because the mean of its divisors is an integer number (27446850).

Almost surely, 2^721642554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721642554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (878299200).

721642554 is an abundant number, since it is smaller than the sum of its proper divisors (1034955846).

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

721642554 is a wasteful number, since it uses less digits than its factorization.

721642554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27164 (or 27158 counting only the distinct ones).

The product of its digits is 67200, while the sum is 36.

The square root of 721642554 is about 26863.4054803184. The cubic root of 721642554 is about 896.9620010525.

It can be divided in two parts, 7216 and 42554, that added together give a triangular number (49770 = T₃₁₅).

The spelling of 721642554 in words is "seven hundred twenty-one million, six hundred forty-two thousand, five hundred fifty-four".