21247432755 has 32 divisors (see below), whose sum is σ = 35613388800. Its totient is φ = 10802692992.

The previous prime is 21247432691. The next prime is 21247432757. The reversal of 21247432755 is 55723474212.

It is not a de Polignac number, because 21247432755 - 2⁶ = 21247432691 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21247432757) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 274779 + ... + 343508.

It is an arithmetic number, because the mean of its divisors is an integer number (1112918400).

Almost surely, 2^21247432755 is an apocalyptic number.

21247432755 is a deficient number, since it is larger than the sum of its proper divisors (14365956045).

21247432755 is a wasteful number, since it uses less digits than its factorization.

21247432755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618403.

The product of its digits is 470400, while the sum is 42.

The spelling of 21247432755 in words is "twenty-one billion, two hundred forty-seven million, four hundred thirty-two thousand, seven hundred fifty-five".