61729621 has 4 divisors (see below), whose sum is σ = 62741644. Its totient is φ = 60717600.

The previous prime is 61729607. The next prime is 61729627. The reversal of 61729621 is 12692716.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 33756100 + 27973521 = 5810^2 + 5289^2 .

It is a cyclic number.

It is not a de Polignac number, because 61729621 - 2⁵ = 61729589 is a prime.

It is a super-2 number, since 2×61729621² = 7621092217607282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61729627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 505920 + ... + 506041.

It is an arithmetic number, because the mean of its divisors is an integer number (15685411).

Almost surely, 2^61729621 is an apocalyptic number.

61729621 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

61729621 is a deficient number, since it is larger than the sum of its proper divisors (1012023).

61729621 is a wasteful number, since it uses less digits than its factorization.

61729621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1012022.

The product of its digits is 9072, while the sum is 34.

The square root of 61729621 is about 7856.8200310304. The cubic root of 61729621 is about 395.2129834672.

The spelling of 61729621 in words is "sixty-one million, seven hundred twenty-nine thousand, six hundred twenty-one".