21709062821 has 8 divisors (see below), whose sum is σ = 22036789920. Its totient is φ = 21381445008.

The previous prime is 21709062773. The next prime is 21709062833. The reversal of 21709062821 is 12826090712.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21709062821 is a prime.

It is a super-2 number, since 2×21709062821² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21709062871) 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, 430295 + ... + 478091.

It is an arithmetic number, because the mean of its divisors is an integer number (2754598740).

Almost surely, 2^21709062821 is an apocalyptic number.

It is an amenable number.

21709062821 is a deficient number, since it is larger than the sum of its proper divisors (327727099).

21709062821 is an equidigital number, since it uses as much as digits as its factorization.

21709062821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54643.

The product of its (nonzero) digits is 24192, while the sum is 38.

The spelling of 21709062821 in words is "twenty-one billion, seven hundred nine million, sixty-two thousand, eight hundred twenty-one".