21531404341551 has 16 divisors (see below), whose sum is σ = 30965884974080. Its totient is φ = 13229096398560.

The previous prime is 21531404341511. The next prime is 21531404341561. The reversal of 21531404341551 is 15514340413512.

It is not a de Polignac number, because 21531404341551 - 2¹³ = 21531404333359 is a prime.

It is a super-2 number, since 2×21531404341551² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531404341511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 437445511 + ... + 437494728.

It is an arithmetic number, because the mean of its divisors is an integer number (1935367810880).

Almost surely, 2^{21531404341551} is an apocalyptic number.

21531404341551 is a deficient number, since it is larger than the sum of its proper divisors (9434480632529).

21531404341551 is a wasteful number, since it uses less digits than its factorization.

21531404341551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 874940886.

The product of its (nonzero) digits is 144000, while the sum is 39.

The spelling of 21531404341551 in words is "twenty-one trillion, five hundred thirty-one billion, four hundred four million, three hundred forty-one thousand, five hundred fifty-one".