21861034631 has 4 divisors (see below), whose sum is σ = 21861827064. Its totient is φ = 21860242200.

The previous prime is 21861034609. The next prime is 21861034693. The reversal of 21861034631 is 13643016812.

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-21861034631 is a prime.

It is a super-2 number, since 2×21861034631² (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 = 21861034591 and 21861034600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861034331) 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, 353285 + ... + 410526.

It is an arithmetic number, because the mean of its divisors is an integer number (5465456766).

Almost surely, 2^21861034631 is an apocalyptic number.

21861034631 is a deficient number, since it is larger than the sum of its proper divisors (792433).

21861034631 is an equidigital number, since it uses as much as digits as its factorization.

21861034631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792432.

The product of its (nonzero) digits is 20736, while the sum is 35.

The spelling of 21861034631 in words is "twenty-one billion, eight hundred sixty-one million, thirty-four thousand, six hundred thirty-one".