21201678431 has 4 divisors (see below), whose sum is σ = 21215600952. Its totient is φ = 21187755912.

The previous prime is 21201678413. The next prime is 21201678437. The reversal of 21201678431 is 13487610212.

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 21201678431 - 2¹⁰ = 21201677407 is a prime.

It is a super-2 number, since 2×21201678431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201678391 and 21201678400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201678437) 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, 6958976 + ... + 6962021.

It is an arithmetic number, because the mean of its divisors is an integer number (5303900238).

Almost surely, 2^21201678431 is an apocalyptic number.

21201678431 is a deficient number, since it is larger than the sum of its proper divisors (13922521).

21201678431 is a wasteful number, since it uses less digits than its factorization.

21201678431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13922520.

The product of its (nonzero) digits is 16128, while the sum is 35.

The spelling of 21201678431 in words is "twenty-one billion, two hundred one million, six hundred seventy-eight thousand, four hundred thirty-one".