21866001631 has 2 divisors, whose sum is σ = 21866001632. Its totient is φ = 21866001630.

The previous prime is 21866001593. The next prime is 21866001671. The reversal of 21866001631 is 13610066812.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21866001631 - 2¹³ = 21865993439 is a prime.

It is a super-2 number, since 2×21866001631² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21866001671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10933000815 + 10933000816.

It is an arithmetic number, because the mean of its divisors is an integer number (10933000816).

Almost surely, 2^21866001631 is an apocalyptic number.

21866001631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21866001631 is an equidigital number, since it uses as much as digits as its factorization.

21866001631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 34.

The spelling of 21866001631 in words is "twenty-one billion, eight hundred sixty-six million, one thousand, six hundred thirty-one".