21261602154215 has 4 divisors (see below), whose sum is σ = 25513922585064. Its totient is φ = 17009281723368.

The previous prime is 21261602154211. The next prime is 21261602154227. The reversal of 21261602154215 is 51245120616212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21261602154215 - 2² = 21261602154211 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261602154211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2126160215417 + ... + 2126160215426.

It is an arithmetic number, because the mean of its divisors is an integer number (6378480646266).

Almost surely, 2^{21261602154215} is an apocalyptic number.

21261602154215 is a deficient number, since it is larger than the sum of its proper divisors (4252320430849).

21261602154215 is an equidigital number, since it uses as much as digits as its factorization.

21261602154215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4252320430848.

The product of its (nonzero) digits is 57600, while the sum is 38.

The spelling of 21261602154215 in words is "twenty-one trillion, two hundred sixty-one billion, six hundred two million, one hundred fifty-four thousand, two hundred fifteen".