21612121557465 has 32 divisors (see below), whose sum is σ = 35516681110656. Its totient is φ = 11214083473920.

The previous prime is 21612121557451. The next prime is 21612121557497. The reversal of 21612121557465 is 56475512121612.

It is not a de Polignac number, because 21612121557465 - 2⁹ = 21612121556953 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5831629 + ... + 8788181.

It is an arithmetic number, because the mean of its divisors is an integer number (1109896284708).

Almost surely, 2^{21612121557465} is an apocalyptic number.

It is an amenable number.

21612121557465 is a deficient number, since it is larger than the sum of its proper divisors (13904559553191).

21612121557465 is a wasteful number, since it uses less digits than its factorization.

21612121557465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2969769.

The product of its digits is 1008000, while the sum is 48.

The spelling of 21612121557465 in words is "twenty-one trillion, six hundred twelve billion, one hundred twenty-one million, five hundred fifty-seven thousand, four hundred sixty-five".