772521661 has 4 divisors (see below), whose sum is σ = 773226972. Its totient is φ = 771816352.

The previous prime is 772521611. The next prime is 772521671. The reversal of 772521661 is 166125277.

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 372721636 + 399800025 = 19306^2 + 19995^2 .

It is a cyclic number.

It is not a de Polignac number, because 772521661 - 2⁹ = 772521149 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 772521661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (772521611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 351010 + ... + 353203.

It is an arithmetic number, because the mean of its divisors is an integer number (193306743).

Almost surely, 2^772521661 is an apocalyptic number.

It is an amenable number.

772521661 is a deficient number, since it is larger than the sum of its proper divisors (705311).

772521661 is a wasteful number, since it uses less digits than its factorization.

772521661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 705310.

The product of its digits is 35280, while the sum is 37.

The square root of 772521661 is about 27794.2738886987. The cubic root of 772521661 is about 917.5651040380.

It can be divided in two parts, 7725216 and 61, that added together give a palindrome (7725277).

The spelling of 772521661 in words is "seven hundred seventy-two million, five hundred twenty-one thousand, six hundred sixty-one".