400021430721 has 16 divisors (see below), whose sum is σ = 583744643328. Its totient is φ = 241647526800.

The previous prime is 400021430719. The next prime is 400021430773. The reversal of 400021430721 is 127034120004.

It is a happy number.

It is not a de Polignac number, because 400021430721 - 2¹ = 400021430719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 400021430691 and 400021430700.

It is not an unprimeable number, because it can be changed into a prime (400021430621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19732315 + ... + 19752576.

It is an arithmetic number, because the mean of its divisors is an integer number (36484040208).

Almost surely, 2^400021430721 is an apocalyptic number.

It is an amenable number.

400021430721 is a deficient number, since it is larger than the sum of its proper divisors (183723212607).

400021430721 is a wasteful number, since it uses less digits than its factorization.

400021430721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39485212.

The product of its (nonzero) digits is 1344, while the sum is 24.

Adding to 400021430721 its reverse (127034120004), we get a palindrome (527055550725).

The spelling of 400021430721 in words is "four hundred billion, twenty-one million, four hundred thirty thousand, seven hundred twenty-one".