21951401681 has 8 divisors (see below), whose sum is σ = 24531056928. Its totient is φ = 19469092000.

The previous prime is 21951401663. The next prime is 21951401729. The reversal of 21951401681 is 18610415912.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21951401681 - 2²² = 21947207377 is a prime.

It is a super-2 number, since 2×21951401681² (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 (21951401611) 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 7 ways as a sum of consecutive naturals, for example, 24335915 + ... + 24336816.

It is an arithmetic number, because the mean of its divisors is an integer number (3066382116).

Almost surely, 2^21951401681 is an apocalyptic number.

It is an amenable number.

21951401681 is a deficient number, since it is larger than the sum of its proper divisors (2579655247).

21951401681 is a wasteful number, since it uses less digits than its factorization.

21951401681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48672783.

The product of its (nonzero) digits is 17280, while the sum is 38.

The spelling of 21951401681 in words is "twenty-one billion, nine hundred fifty-one million, four hundred one thousand, six hundred eighty-one".