621031681 has 2 divisors, whose sum is σ = 621031682. Its totient is φ = 621031680.

The previous prime is 621031673. The next prime is 621031693. The reversal of 621031681 is 186130126.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 621006400 + 25281 = 24920^2 + 159^2 .

It is a cyclic number.

It is not a de Polignac number, because 621031681 - 2³ = 621031673 is a prime.

It is a super-2 number, since 2×621031681² = 771360697611371522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (621031661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310515840 + 310515841.

It is an arithmetic number, because the mean of its divisors is an integer number (310515841).

Almost surely, 2^621031681 is an apocalyptic number.

It is an amenable number.

621031681 is a deficient number, since it is larger than the sum of its proper divisors (1).

621031681 is an equidigital number, since it uses as much as digits as its factorization.

621031681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 621031681 is about 24920.5072380158. The cubic root of 621031681 is about 853.1746020099.

The spelling of 621031681 in words is "six hundred twenty-one million, thirty-one thousand, six hundred eighty-one".