1721040638 has 4 divisors (see below), whose sum is σ = 2581560960. Its totient is φ = 860520318.

The previous prime is 1721040631. The next prime is 1721040649. The reversal of 1721040638 is 8360401271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8360401271 = 29 ⋅288289699.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721040631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430260158 + ... + 430260161.

It is an arithmetic number, because the mean of its divisors is an integer number (645390240).

Almost surely, 2^1721040638 is an apocalyptic number.

1721040638 is a deficient number, since it is larger than the sum of its proper divisors (860520322).

1721040638 is an equidigital number, since it uses as much as digits as its factorization.

1721040638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860520321.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 1721040638 is about 41485.4268147262. The cubic root of 1721040638 is about 1198.3868690529.

The spelling of 1721040638 in words is "one billion, seven hundred twenty-one million, forty thousand, six hundred thirty-eight".