21661465732431 has 16 divisors (see below), whose sum is σ = 33500603721984. Its totient is φ = 12193234441344.

The previous prime is 21661465732429. The next prime is 21661465732433. The reversal of 21661465732431 is 13423756416612.

It is an interprime number because it is at equal distance from previous prime (21661465732429) and next prime (21661465732433).

It is not a de Polignac number, because 21661465732431 - 2¹ = 21661465732429 is a prime.

It is a super-2 number, since 2×21661465732431² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661465732433) 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, 7697747610 + ... + 7697750423.

It is an arithmetic number, because the mean of its divisors is an integer number (2093787732624).

Almost surely, 2^{21661465732431} is an apocalyptic number.

21661465732431 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21661465732431 is a deficient number, since it is larger than the sum of its proper divisors (11839137989553).

21661465732431 is a wasteful number, since it uses less digits than its factorization.

21661465732431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15395498110.

The product of its digits is 4354560, while the sum is 51.

The spelling of 21661465732431 in words is "twenty-one trillion, six hundred sixty-one billion, four hundred sixty-five million, seven hundred thirty-two thousand, four hundred thirty-one".