61102401721 has 9 divisors (see below), whose sum is σ = 62639442733. Its totient is φ = 59602211680.

The previous prime is 61102401713. The next prime is 61102401743. The reversal of 61102401721 is 12710420116.

The square root of 61102401721 is 247189.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 83521321 + 61018880400 = 9139^2 + 247020^2 .

It is not a de Polignac number, because 61102401721 - 2³ = 61102401713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61102401761) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 10131735 + ... + 10137763.

Almost surely, 2^61102401721 is an apocalyptic number.

61102401721 is the 247189-th square number.

61102401721 is the 123595-th centered octagonal number.

It is an amenable number.

61102401721 is a deficient number, since it is larger than the sum of its proper divisors (1537041012).

61102401721 is an frugal number, since it uses more digits than its factorization.

61102401721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12140 (or 6070 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

Multiplying 61102401721 by its sum of digits (25), we get a square (1527560043025 = 1235945²).

Adding to 61102401721 its reverse (12710420116), we get a palindrome (73812821837).

The spelling of 61102401721 in words is "sixty-one billion, one hundred two million, four hundred one thousand, seven hundred twenty-one".