21401723 has 8 divisors (see below), whose sum is σ = 24488448. Its totient is φ = 18322344.

The previous prime is 21401717. The next prime is 21401761. The reversal of 21401723 is 32710412.

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 21401723 - 2¹⁴ = 21385339 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21401695 and 21401704.

It is not an unprimeable number, because it can be changed into a prime (21401123) 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, 7790 + ... + 10172.

It is an arithmetic number, because the mean of its divisors is an integer number (3061056).

Almost surely, 2^21401723 is an apocalyptic number.

21401723 is a deficient number, since it is larger than the sum of its proper divisors (3086725).

21401723 is a wasteful number, since it uses less digits than its factorization.

21401723 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3673.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21401723 is about 4626.1996282046. The cubic root of 21401723 is about 277.6405607737.

The spelling of 21401723 in words is "twenty-one million, four hundred one thousand, seven hundred twenty-three".