21531861942 has 32 divisors (see below), whose sum is σ = 44743298400. Its totient is φ = 6899520768.

The previous prime is 21531861917. The next prime is 21531861943. The reversal of 21531861942 is 24916813512.

It is a super-2 number, since 2×21531861942² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21531861894 and 21531861903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531861943) 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, 230343 + ... + 310034.

It is an arithmetic number, because the mean of its divisors is an integer number (1398228075).

Almost surely, 2^21531861942 is an apocalyptic number.

21531861942 is an abundant number, since it is smaller than the sum of its proper divisors (23211436458).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21531861942 is a wasteful number, since it uses less digits than its factorization.

21531861942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540640.

The product of its digits is 103680, while the sum is 42.

The spelling of 21531861942 in words is "twenty-one billion, five hundred thirty-one million, eight hundred sixty-one thousand, nine hundred forty-two".