21729519 has 32 divisors (see below), whose sum is σ = 38960640. Its totient is φ = 11684736.

The previous prime is 21729517. The next prime is 21729527. The reversal of 21729519 is 91592712.

It is not a de Polignac number, because 21729519 - 2¹ = 21729517 is a prime.

It is a super-2 number, since 2×21729519² = 944343991942722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21729511) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 169 + ... + 6594.

It is an arithmetic number, because the mean of its divisors is an integer number (1217520).

Almost surely, 2^21729519 is an apocalyptic number.

21729519 is a deficient number, since it is larger than the sum of its proper divisors (17231121).

21729519 is a wasteful number, since it uses less digits than its factorization.

21729519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6796 (or 6790 counting only the distinct ones).

The product of its digits is 11340, while the sum is 36.

The square root of 21729519 is about 4661.4932156982. The cubic root of 21729519 is about 279.0508636599.

The spelling of 21729519 in words is "twenty-one million, seven hundred twenty-nine thousand, five hundred nineteen".