21035790721 has 4 divisors (see below), whose sum is σ = 22948135344. Its totient is φ = 19123446100.

The previous prime is 21035790719. The next prime is 21035790733. The reversal of 21035790721 is 12709753012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21035790721 - 2¹ = 21035790719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21035790751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 956172295 + ... + 956172316.

It is an arithmetic number, because the mean of its divisors is an integer number (5737033836).

Almost surely, 2^21035790721 is an apocalyptic number.

It is an amenable number.

21035790721 is a deficient number, since it is larger than the sum of its proper divisors (1912344623).

21035790721 is a wasteful number, since it uses less digits than its factorization.

21035790721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1912344622.

The product of its (nonzero) digits is 26460, while the sum is 37.

The spelling of 21035790721 in words is "twenty-one billion, thirty-five million, seven hundred ninety thousand, seven hundred twenty-one".