21655254237 has 16 divisors (see below), whose sum is σ = 30443958720. Its totient is φ = 13654224000.

The previous prime is 21655254233. The next prime is 21655254263. The reversal of 21655254237 is 73245255612.

It is not a de Polignac number, because 21655254237 - 2² = 21655254233 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21655254233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 281814 + ... + 350327.

It is an arithmetic number, because the mean of its divisors is an integer number (1902747420).

Almost surely, 2^21655254237 is an apocalyptic number.

It is an amenable number.

21655254237 is a deficient number, since it is larger than the sum of its proper divisors (8788704483).

21655254237 is a wasteful number, since it uses less digits than its factorization.

21655254237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 632764.

The product of its digits is 504000, while the sum is 42.

The spelling of 21655254237 in words is "twenty-one billion, six hundred fifty-five million, two hundred fifty-four thousand, two hundred thirty-seven".