20721749475 has 24 divisors (see below), whose sum is σ = 39154240000. Its totient is φ = 9472799520.

The previous prime is 20721749431. The next prime is 20721749501. The reversal of 20721749475 is 57494712702.

It is not a de Polignac number, because 20721749475 - 2⁹ = 20721748963 is a prime.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 19734475 + ... + 19735524.

Almost surely, 2^20721749475 is an apocalyptic number.

20721749475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20721749475 is a deficient number, since it is larger than the sum of its proper divisors (18432490525).

20721749475 is a wasteful number, since it uses less digits than its factorization.

20721749475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39470019 (or 39470014 counting only the distinct ones).

The product of its (nonzero) digits is 987840, while the sum is 48.

The spelling of 20721749475 in words is "twenty billion, seven hundred twenty-one million, seven hundred forty-nine thousand, four hundred seventy-five".