21405723435 has 12 divisors (see below), whose sum is σ = 37103254032. Its totient is φ = 11416385808.

The previous prime is 21405723431. The next prime is 21405723457. The reversal of 21405723435 is 53432750412.

21405723435 is a `hidden beast` number, since 2 + 1 + 40 + 572 + 3 + 43 + 5 = 666.

It is not a de Polignac number, because 21405723435 - 2² = 21405723431 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21405723435.

It is not an unprimeable number, because it can be changed into a prime (21405723431) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 237841327 + ... + 237841416.

It is an arithmetic number, because the mean of its divisors is an integer number (3091937836).

Almost surely, 2^21405723435 is an apocalyptic number.

21405723435 is a deficient number, since it is larger than the sum of its proper divisors (15697530597).

21405723435 is a wasteful number, since it uses less digits than its factorization.

21405723435 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475682754 (or 475682751 counting only the distinct ones).

The product of its (nonzero) digits is 100800, while the sum is 36.

The spelling of 21405723435 in words is "twenty-one billion, four hundred five million, seven hundred twenty-three thousand, four hundred thirty-five".