21521800292121 has 16 divisors (see below), whose sum is σ = 32287745401600. Its totient is φ = 14166248292144.

The previous prime is 21521800292107. The next prime is 21521800292131. The reversal of 21521800292121 is 12129200812512.

21521800292121 is a `hidden beast` number, since 2 + 1 + 521 + 8 + 0 + 0 + 2 + 9 + 2 + 121 = 666.

It is not a de Polignac number, because 21521800292121 - 2³⁷ = 21384361338649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21521800292131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5044958086 + ... + 5044962351.

It is an arithmetic number, because the mean of its divisors is an integer number (2017984087600).

Almost surely, 2^{21521800292121} is an apocalyptic number.

It is an amenable number.

21521800292121 is a deficient number, since it is larger than the sum of its proper divisors (10765945109479).

21521800292121 is a wasteful number, since it uses less digits than its factorization.

21521800292121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10089920525 (or 10089920519 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 36.

The spelling of 21521800292121 in words is "twenty-one trillion, five hundred twenty-one billion, eight hundred million, two hundred ninety-two thousand, one hundred twenty-one".