621071662561 has 9 divisors (see below), whose sum is σ = 722477534961. Its totient is φ = 532342410852.

The previous prime is 621071662537. The next prime is 621071662633. The reversal of 621071662561 is 165266170126.

The square root of 621071662561 is 788081.

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

It is not a de Polignac number, because 621071662561 - 2⁷ = 621071662433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (621071662511) 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 8 ways as a sum of consecutive naturals, for example, 5460276 + ... + 5572858.

Almost surely, 2^621071662561 is an apocalyptic number.

621071662561 is the 788081-st square number.

621071662561 is the 394041-st centered octagonal number.

It is an amenable number.

621071662561 is a deficient number, since it is larger than the sum of its proper divisors (101405872400).

621071662561 is an frugal number, since it uses more digits than its factorization.

621071662561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225180 (or 112590 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 43.

The spelling of 621071662561 in words is "six hundred twenty-one billion, seventy-one million, six hundred sixty-two thousand, five hundred sixty-one".