21500491747 has 8 divisors (see below), whose sum is σ = 25640338176. Its totient is φ = 17627732232.

The previous prime is 21500491739. The next prime is 21500491769. The reversal of 21500491747 is 74719400512.

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 21500491747 - 2³ = 21500491739 is a prime.

It is a super-2 number, since 2×21500491747² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21500491147) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66771553 + ... + 66771874.

It is an arithmetic number, because the mean of its divisors is an integer number (3205042272).

Almost surely, 2^21500491747 is an apocalyptic number.

21500491747 is a deficient number, since it is larger than the sum of its proper divisors (4139846429).

21500491747 is a wasteful number, since it uses less digits than its factorization.

21500491747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133543457.

The product of its (nonzero) digits is 70560, while the sum is 40.

The spelling of 21500491747 in words is "twenty-one billion, five hundred million, four hundred ninety-one thousand, seven hundred forty-seven".