21424150257661 has 2 divisors, whose sum is σ = 21424150257662. Its totient is φ = 21424150257660.

The previous prime is 21424150257649. The next prime is 21424150257689. The reversal of 21424150257661 is 16675205142412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21067466584761 + 356683672900 = 4589931^2 + 597230^2 .

It is a cyclic number.

It is not a de Polignac number, because 21424150257661 - 2⁹ = 21424150257149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21424150257611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712075128830 + 10712075128831.

It is an arithmetic number, because the mean of its divisors is an integer number (10712075128831).

Almost surely, 2^{21424150257661} is an apocalyptic number.

It is an amenable number.

21424150257661 is a deficient number, since it is larger than the sum of its proper divisors (1).

21424150257661 is an equidigital number, since it uses as much as digits as its factorization.

21424150257661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 806400, while the sum is 46.

The spelling of 21424150257661 in words is "twenty-one trillion, four hundred twenty-four billion, one hundred fifty million, two hundred fifty-seven thousand, six hundred sixty-one".