21054142531 has 4 divisors (see below), whose sum is σ = 21054959464. Its totient is φ = 21053325600.

The previous prime is 21054142519. The next prime is 21054142537. The reversal of 21054142531 is 13524145012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21054142531 is a prime.

It is a super-2 number, since 2×21054142531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21054142531.

It is not an unprimeable number, because it can be changed into a prime (21054142537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 368505 + ... + 421786.

It is an arithmetic number, because the mean of its divisors is an integer number (5263739866).

Almost surely, 2^21054142531 is an apocalyptic number.

21054142531 is a deficient number, since it is larger than the sum of its proper divisors (816933).

21054142531 is an equidigital number, since it uses as much as digits as its factorization.

21054142531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816932.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 21054142531 its reverse (13524145012), we get a palindrome (34578287543).

The spelling of 21054142531 in words is "twenty-one billion, fifty-four million, one hundred forty-two thousand, five hundred thirty-one".