621436661 has 2 divisors, whose sum is σ = 621436662. Its totient is φ = 621436660.

The previous prime is 621436657. The next prime is 621436681. The reversal of 621436661 is 166634126.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 567868900 + 53567761 = 23830^2 + 7319^2 .

It is a cyclic number.

It is not a de Polignac number, because 621436661 - 2² = 621436657 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (621436681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310718330 + 310718331.

It is an arithmetic number, because the mean of its divisors is an integer number (310718331).

Almost surely, 2^621436661 is an apocalyptic number.

It is an amenable number.

621436661 is a deficient number, since it is larger than the sum of its proper divisors (1).

621436661 is an equidigital number, since it uses as much as digits as its factorization.

621436661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 35.

The square root of 621436661 is about 24928.6313503168. The cubic root of 621436661 is about 853.3600158317.

It can be divided in two parts, 6214 and 36661, that added together give a cube (42875 = 35³).

The spelling of 621436661 in words is "six hundred twenty-one million, four hundred thirty-six thousand, six hundred sixty-one".