1721572421 has 8 divisors (see below), whose sum is σ = 1731003744. Its totient is φ = 1712153520.

The previous prime is 1721572409. The next prime is 1721572427. The reversal of 1721572421 is 1242751271.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1721572421 - 2⁶ = 1721572357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721572427) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 437555 + ... + 441471.

It is an arithmetic number, because the mean of its divisors is an integer number (216375468).

Almost surely, 2^1721572421 is an apocalyptic number.

It is an amenable number.

1721572421 is a deficient number, since it is larger than the sum of its proper divisors (9431323).

1721572421 is a wasteful number, since it uses less digits than its factorization.

1721572421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6211.

The product of its digits is 7840, while the sum is 32.

The square root of 1721572421 is about 41491.8355944877. The cubic root of 1721572421 is about 1198.5102858826.

The spelling of 1721572421 in words is "one billion, seven hundred twenty-one million, five hundred seventy-two thousand, four hundred twenty-one".