21421512061 has 2 divisors, whose sum is σ = 21421512062. Its totient is φ = 21421512060.

The previous prime is 21421512043. The next prime is 21421512067. The reversal of 21421512061 is 16021512412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14533508025 + 6888004036 = 120555^2 + 82994^2 .

It is a cyclic number.

It is not a de Polignac number, because 21421512061 - 2⁷ = 21421511933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21421512067) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710756030 + 10710756031.

It is an arithmetic number, because the mean of its divisors is an integer number (10710756031).

Almost surely, 2^21421512061 is an apocalyptic number.

It is an amenable number.

21421512061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421512061 is an equidigital number, since it uses as much as digits as its factorization.

21421512061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 960, while the sum is 25.

The spelling of 21421512061 in words is "twenty-one billion, four hundred twenty-one million, five hundred twelve thousand, sixty-one".