21900431220642 has 90 divisors (see below), whose sum is σ = 53140301902017. Its totient is φ = 6738355965744.

The previous prime is 21900431220637. The next prime is 21900431220727. The reversal of 21900431220642 is 24602213400912.

It is a happy number.

21900431220642 is a `hidden beast` number, since 2 + 1 + 9 + 0 + 0 + 4 + 3 + 1 + 2 + 2 + 0 + 642 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 18725516635401 + 3174914585241 = 4327299^2 + 1781829^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3309111.

It is a junction number, because it is equal to n+sod(n) for n = 21900431220597 and 21900431220606.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 774317833 + ... + 774346115.

Almost surely, 2^{21900431220642} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21900431220642

21900431220642 is an abundant number, since it is smaller than the sum of its proper divisors (31239870681375).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21900431220642 is an frugal number, since it uses more digits than its factorization.

21900431220642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56606 (or 28301 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The spelling of 21900431220642 in words is "twenty-one trillion, nine hundred billion, four hundred thirty-one million, two hundred twenty thousand, six hundred forty-two".