21461251615 has 16 divisors (see below), whose sum is σ = 26020022688. Its totient is φ = 16991640576.

The previous prime is 21461251589. The next prime is 21461251619. The reversal of 21461251615 is 51615216412.

It is a cyclic number.

It is not a de Polignac number, because 21461251615 - 2¹¹ = 21461249567 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 (21461251619) 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, 533239 + ... + 572071.

It is an arithmetic number, because the mean of its divisors is an integer number (1626251418).

Almost surely, 2^21461251615 is an apocalyptic number.

21461251615 is a deficient number, since it is larger than the sum of its proper divisors (4558771073).

21461251615 is a wasteful number, since it uses less digits than its factorization.

21461251615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39978.

The product of its digits is 14400, while the sum is 34.

The spelling of 21461251615 in words is "twenty-one billion, four hundred sixty-one million, two hundred fifty-one thousand, six hundred fifteen".