21142512431 has 4 divisors (see below), whose sum is σ = 21163384632. Its totient is φ = 21121640232.

The previous prime is 21142512427. The next prime is 21142512439. The reversal of 21142512431 is 13421524112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21142512431 - 2² = 21142512427 is a prime.

It is a super-2 number, since 2×21142512431² (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 21142512431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21142512439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10434581 + ... + 10436606.

It is an arithmetic number, because the mean of its divisors is an integer number (5290846158).

Almost surely, 2^21142512431 is an apocalyptic number.

21142512431 is a deficient number, since it is larger than the sum of its proper divisors (20872201).

21142512431 is a wasteful number, since it uses less digits than its factorization.

21142512431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20872200.

The product of its digits is 1920, while the sum is 26.

The spelling of 21142512431 in words is "twenty-one billion, one hundred forty-two million, five hundred twelve thousand, four hundred thirty-one".