21649949187 has 4 divisors (see below), whose sum is σ = 28866598920. Its totient is φ = 14433299456.

The previous prime is 21649949179. The next prime is 21649949201. The reversal of 21649949187 is 78194994612.

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 21649949187 - 2³ = 21649949179 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21649949187.

It is not an unprimeable number, because it can be changed into a prime (21649949117) 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, 3608324862 + ... + 3608324867.

It is an arithmetic number, because the mean of its divisors is an integer number (7216649730).

Almost surely, 2^21649949187 is an apocalyptic number.

21649949187 is a deficient number, since it is larger than the sum of its proper divisors (7216649733).

21649949187 is an equidigital number, since it uses as much as digits as its factorization.

21649949187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7216649732.

The product of its digits is 7838208, while the sum is 60.

The spelling of 21649949187 in words is "twenty-one billion, six hundred forty-nine million, nine hundred forty-nine thousand, one hundred eighty-seven".