21742455 has 32 divisors (see below), whose sum is σ = 40518144. Its totient is φ = 9749376.

The previous prime is 21742451. The next prime is 21742471. The reversal of 21742455 is 55424712.

It is not a de Polignac number, because 21742455 - 2² = 21742451 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742451) 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, 3612 + ... + 7518.

It is an arithmetic number, because the mean of its divisors is an integer number (1266192).

Almost surely, 2^21742455 is an apocalyptic number.

21742455 is a deficient number, since it is larger than the sum of its proper divisors (18775689).

21742455 is a wasteful number, since it uses less digits than its factorization.

21742455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3975.

The product of its digits is 11200, while the sum is 30.

The square root of 21742455 is about 4662.8805474728. The cubic root of 21742455 is about 279.1062274545.

The spelling of 21742455 in words is "twenty-one million, seven hundred forty-two thousand, four hundred fifty-five".