61728321 has 16 divisors (see below), whose sum is σ = 88980800. Its totient is φ = 37931328.

The previous prime is 61728319. The next prime is 61728367. The reversal of 61728321 is 12382716.

It is not a de Polignac number, because 61728321 - 2¹ = 61728319 is a prime.

It is a super-2 number, since 2×61728321² = 7620771226958082, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (61728391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12526 + ... + 16743.

It is an arithmetic number, because the mean of its divisors is an integer number (5561300).

Almost surely, 2^61728321 is an apocalyptic number.

It is an amenable number.

61728321 is a deficient number, since it is larger than the sum of its proper divisors (27252479).

61728321 is a wasteful number, since it uses less digits than its factorization.

61728321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29328.

The product of its digits is 4032, while the sum is 30.

The square root of 61728321 is about 7856.7372999229. The cubic root of 61728321 is about 395.2102091077.

The spelling of 61728321 in words is "sixty-one million, seven hundred twenty-eight thousand, three hundred twenty-one".