21951341787 has 4 divisors (see below), whose sum is σ = 29268455720. Its totient is φ = 14634227856.

The previous prime is 21951341777. The next prime is 21951341791. The reversal of 21951341787 is 78714315912.

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

It is not a de Polignac number, because 21951341787 - 2²⁴ = 21934564571 is a prime.

It is a super-2 number, since 2×21951341787² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21951341777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3658556962 + ... + 3658556967.

It is an arithmetic number, because the mean of its divisors is an integer number (7317113930).

Almost surely, 2^21951341787 is an apocalyptic number.

21951341787 is a deficient number, since it is larger than the sum of its proper divisors (7317113933).

21951341787 is an equidigital number, since it uses as much as digits as its factorization.

21951341787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7317113932.

The product of its digits is 423360, while the sum is 48.

The spelling of 21951341787 in words is "twenty-one billion, nine hundred fifty-one million, three hundred forty-one thousand, seven hundred eighty-seven".