21623408401 has 15 divisors (see below), whose sum is σ = 25234217403. Its totient is φ = 18528174000.

The previous prime is 21623408399. The next prime is 21623408431. The reversal of 21623408401 is 10480432612.

The square root of 21623408401 is 147049.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 11631406801 + 9992001600 = 107849^2 + 99960^2 .

It is not a de Polignac number, because 21623408401 - 2¹ = 21623408399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21623408431) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 7203901 + ... + 7206901.

Almost surely, 2^21623408401 is an apocalyptic number.

21623408401 is the 147049-th square number.

21623408401 is the 73525-th centered octagonal number.

It is an amenable number.

21623408401 is a deficient number, since it is larger than the sum of its proper divisors (3610809002).

21623408401 is an frugal number, since it uses more digits than its factorization.

21623408401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6030 (or 3008 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 31.

Multiplying 21623408401 by its product of nonzero digits (9216), we get a square (199281331823616 = 14116704²).

The spelling of 21623408401 in words is "twenty-one billion, six hundred twenty-three million, four hundred eight thousand, four hundred one".