21655610407 has 2 divisors, whose sum is σ = 21655610408. Its totient is φ = 21655610406.

The previous prime is 21655610401. The next prime is 21655610441. The reversal of 21655610407 is 70401655612.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21655610407 - 2¹⁵ = 21655577639 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21655610401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10827805203 + 10827805204.

It is an arithmetic number, because the mean of its divisors is an integer number (10827805204).

Almost surely, 2^21655610407 is an apocalyptic number.

21655610407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21655610407 is an equidigital number, since it uses as much as digits as its factorization.

21655610407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 50400, while the sum is 37.

The spelling of 21655610407 in words is "twenty-one billion, six hundred fifty-five million, six hundred ten thousand, four hundred seven".