721978534 has 4 divisors (see below), whose sum is σ = 1082967804. Its totient is φ = 360989266.

The previous prime is 721978531. The next prime is 721978573. The reversal of 721978534 is 435879127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 435879127 = 31 ⋅14060617.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721978531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180494632 + ... + 180494635.

It is an arithmetic number, because the mean of its divisors is an integer number (270741951).

Almost surely, 2^721978534 is an apocalyptic number.

721978534 is a deficient number, since it is larger than the sum of its proper divisors (360989270).

721978534 is a wasteful number, since it uses less digits than its factorization.

721978534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360989269.

The product of its digits is 423360, while the sum is 46.

The square root of 721978534 is about 26869.6582412207. The cubic root of 721978534 is about 897.1011810082.

The spelling of 721978534 in words is "seven hundred twenty-one million, nine hundred seventy-eight thousand, five hundred thirty-four".