64049992561 has 3 divisors (see below), whose sum is σ = 64050245643. Its totient is φ = 64049739480.

The previous prime is 64049992547. The next prime is 64049992621. The reversal of 64049992561 is 16529994046.

The square root of 64049992561 is 253081.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16529994046 = 2 ⋅8264997023.

It can be written as a sum of positive squares in only one way, i.e., 1749832561 + 62300160000 = 41831^2 + 249600^2 .

It is not a de Polignac number, because 64049992561 - 2¹¹ = 64049990513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64049992511) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 126541 + ... + 379621.

It is an arithmetic number, because the mean of its divisors is an integer number (21350081881).

Almost surely, 2^64049992561 is an apocalyptic number.

64049992561 is the 253081-st square number.

64049992561 is the 126541-st centered octagonal number.

It is an amenable number.

64049992561 is a deficient number, since it is larger than the sum of its proper divisors (253082).

64049992561 is an frugal number, since it uses more digits than its factorization.

64049992561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506162 (or 253081 counting only the distinct ones).

The product of its (nonzero) digits is 4199040, while the sum is 55.

The spelling of 64049992561 in words is "sixty-four billion, forty-nine million, nine hundred ninety-two thousand, five hundred sixty-one".