621059981 has 2 divisors, whose sum is σ = 621059982. Its totient is φ = 621059980.

The previous prime is 621059939. The next prime is 621059987. The reversal of 621059981 is 189950126.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 581243881 + 39816100 = 24109^2 + 6310^2 .

It is a cyclic number.

It is not a de Polignac number, because 621059981 - 2²² = 616865677 is a prime.

It is a super-2 number, since 2×621059981² = 771430999999440722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (621059987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310529990 + 310529991.

It is an arithmetic number, because the mean of its divisors is an integer number (310529991).

Almost surely, 2^621059981 is an apocalyptic number.

It is an amenable number.

621059981 is a deficient number, since it is larger than the sum of its proper divisors (1).

621059981 is an equidigital number, since it uses as much as digits as its factorization.

621059981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 621059981 is about 24921.0750370043. The cubic root of 621059981 is about 853.1875613458.

The spelling of 621059981 in words is "six hundred twenty-one million, fifty-nine thousand, nine hundred eighty-one".