621676661 has 6 divisors (see below), whose sum is σ = 635187510. Its totient is φ = 608447336.

The previous prime is 621676651. The next prime is 621676669. The reversal of 621676661 is 166676126.

It can be written as a sum of positive squares in only one way, i.e., 620508100 + 1168561 = 24910^2 + 1081^2 .

It is a de Polignac number, because none of the positive numbers 2^k-621676661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621676669) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 138506 + ... + 142923.

It is an arithmetic number, because the mean of its divisors is an integer number (105864585).

Almost surely, 2^621676661 is an apocalyptic number.

It is an amenable number.

621676661 is a deficient number, since it is larger than the sum of its proper divisors (13510849).

621676661 is an equidigital number, since it uses as much as digits as its factorization.

621676661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281523 (or 281476 counting only the distinct ones).

The product of its digits is 108864, while the sum is 41.

The square root of 621676661 is about 24933.4446276482. Note that the first 3 decimals coincide. The cubic root of 621676661 is about 853.4698581035.

The spelling of 621676661 in words is "six hundred twenty-one million, six hundred seventy-six thousand, six hundred sixty-one".