721021694 has 4 divisors (see below), whose sum is σ = 1081532544. Its totient is φ = 360510846.

The previous prime is 721021681. The next prime is 721021727. The reversal of 721021694 is 496120127.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 496120127 = 347 ⋅1429741.

It is a self number, because there is not a number n which added to its sum of digits gives 721021694.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180255422 + ... + 180255425.

It is an arithmetic number, because the mean of its divisors is an integer number (270383136).

Almost surely, 2^721021694 is an apocalyptic number.

721021694 is a deficient number, since it is larger than the sum of its proper divisors (360510850).

721021694 is a wasteful number, since it uses less digits than its factorization.

721021694 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360510849.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 721021694 is about 26851.8471245462. The cubic root of 721021694 is about 896.7046956381.

The spelling of 721021694 in words is "seven hundred twenty-one million, twenty-one thousand, six hundred ninety-four".