21909543951 has 32 divisors (see below), whose sum is σ = 31255538688. Its totient is φ = 13603276800.

The previous prime is 21909543949. The next prime is 21909543979. The reversal of 21909543951 is 15934590912.

It is not a de Polignac number, because 21909543951 - 2¹ = 21909543949 is a prime.

It is a super-2 number, since 2×21909543951² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21909543951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909547951) 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 31 ways as a sum of consecutive naturals, for example, 6552186 + ... + 6555528.

It is an arithmetic number, because the mean of its divisors is an integer number (976735584).

Almost surely, 2^21909543951 is an apocalyptic number.

21909543951 is a deficient number, since it is larger than the sum of its proper divisors (9345994737).

21909543951 is a wasteful number, since it uses less digits than its factorization.

21909543951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4671.

The product of its (nonzero) digits is 437400, while the sum is 48.

The spelling of 21909543951 in words is "twenty-one billion, nine hundred nine million, five hundred forty-three thousand, nine hundred fifty-one".