21661715254 has 8 divisors (see below), whose sum is σ = 32596383960. Its totient is φ = 10796253936.

The previous prime is 21661715237. The next prime is 21661715267. The reversal of 21661715254 is 45251716612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17301064 + ... + 17302315.

It is an arithmetic number, because the mean of its divisors is an integer number (4074547995).

Almost surely, 2^21661715254 is an apocalyptic number.

21661715254 is a deficient number, since it is larger than the sum of its proper divisors (10934668706).

21661715254 is a wasteful number, since it uses less digits than its factorization.

21661715254 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34603694.

The product of its digits is 100800, while the sum is 40.

The spelling of 21661715254 in words is "twenty-one billion, six hundred sixty-one million, seven hundred fifteen thousand, two hundred fifty-four".