21155631454 has 4 divisors (see below), whose sum is σ = 31733447184. Its totient is φ = 10577815726.

The previous prime is 21155631443. The next prime is 21155631463. The reversal of 21155631454 is 45413655112.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5288907862 + ... + 5288907865.

It is an arithmetic number, because the mean of its divisors is an integer number (7933361796).

Almost surely, 2^21155631454 is an apocalyptic number.

21155631454 is a deficient number, since it is larger than the sum of its proper divisors (10577815730).

21155631454 is a wasteful number, since it uses less digits than its factorization.

21155631454 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10577815729.

The product of its digits is 72000, while the sum is 37.

The spelling of 21155631454 in words is "twenty-one billion, one hundred fifty-five million, six hundred thirty-one thousand, four hundred fifty-four".