21530842252261 has 2 divisors, whose sum is σ = 21530842252262. Its totient is φ = 21530842252260.

The previous prime is 21530842252201. The next prime is 21530842252273. The reversal of 21530842252261 is 16225224803512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12155647385025 + 9375194867236 = 3486495^2 + 3061894^2 .

It is a cyclic number.

It is not a de Polignac number, because 21530842252261 - 2¹³ = 21530842244069 is a prime.

It is a super-2 number, since 2×21530842252261² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21530842252201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765421126130 + 10765421126131.

It is an arithmetic number, because the mean of its divisors is an integer number (10765421126131).

Almost surely, 2^{21530842252261} is an apocalyptic number.

It is an amenable number.

21530842252261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21530842252261 is an equidigital number, since it uses as much as digits as its factorization.

21530842252261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 460800, while the sum is 43.

The spelling of 21530842252261 in words is "twenty-one trillion, five hundred thirty billion, eight hundred forty-two million, two hundred fifty-two thousand, two hundred sixty-one".