21611251157655 has 32 divisors (see below), whose sum is σ = 34831223294400. Its totient is φ = 11441597468672.

The previous prime is 21611251157653. The next prime is 21611251157659. The reversal of 21611251157655 is 55675115211612.

It is a cyclic number.

It is not a de Polignac number, because 21611251157655 - 2¹ = 21611251157653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21611251157653) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 110068411 + ... + 110264579.

It is an arithmetic number, because the mean of its divisors is an integer number (1088475727950).

Almost surely, 2^{21611251157655} is an apocalyptic number.

21611251157655 is a deficient number, since it is larger than the sum of its proper divisors (13219972136745).

21611251157655 is a wasteful number, since it uses less digits than its factorization.

21611251157655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249923.

The product of its digits is 630000, while the sum is 48.

The spelling of 21611251157655 in words is "twenty-one trillion, six hundred eleven billion, two hundred fifty-one million, one hundred fifty-seven thousand, six hundred fifty-five".