21621340254405 has 16 divisors (see below), whose sum is σ = 34597828387584. Its totient is φ = 11530153475520.

The previous prime is 21621340254401. The next prime is 21621340254433. The reversal of 21621340254405 is 50445204312612.

It is not a de Polignac number, because 21621340254405 - 2² = 21621340254401 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621340254401) 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, 76604034 + ... + 76885763.

It is an arithmetic number, because the mean of its divisors is an integer number (2162364274224).

Almost surely, 2^{21621340254405} is an apocalyptic number.

It is an amenable number.

21621340254405 is a deficient number, since it is larger than the sum of its proper divisors (12976488133179).

21621340254405 is a wasteful number, since it uses less digits than its factorization.

21621340254405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153499196.

The product of its (nonzero) digits is 230400, while the sum is 39.

The spelling of 21621340254405 in words is "twenty-one trillion, six hundred twenty-one billion, three hundred forty million, two hundred fifty-four thousand, four hundred five".