21205454031 has 24 divisors (see below), whose sum is σ = 31328706240. Its totient is φ = 13815438336.

The previous prime is 21205454027. The next prime is 21205454047. The reversal of 21205454031 is 13045450212.

21205454031 is a `hidden beast` number, since 2 + 1 + 205 + 454 + 0 + 3 + 1 = 666.

It is not a de Polignac number, because 21205454031 - 2² = 21205454027 is a prime.

It is a super-2 number, since 2×21205454031² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21205453986 and 21205454004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205454021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 247435 + ... + 321923.

It is an arithmetic number, because the mean of its divisors is an integer number (1305362760).

Almost surely, 2^21205454031 is an apocalyptic number.

21205454031 is a deficient number, since it is larger than the sum of its proper divisors (10123252209).

21205454031 is a wasteful number, since it uses less digits than its factorization.

21205454031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75215 (or 75212 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

It can be divided in two parts, 212054 and 54031, that added together give a triangular number (266085 = T₇₂₉).

The spelling of 21205454031 in words is "twenty-one billion, two hundred five million, four hundred fifty-four thousand, thirty-one".