21554157 has 8 divisors (see below), whose sum is σ = 28765440. Its totient is φ = 14356160.

The previous prime is 21554149. The next prime is 21554161. The reversal of 21554157 is 75145512.

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

It is a cyclic number.

It is not a de Polignac number, because 21554157 - 2³ = 21554149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21554177) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1444 + ... + 6722.

It is an arithmetic number, because the mean of its divisors is an integer number (3595680).

Almost surely, 2^21554157 is an apocalyptic number.

It is an amenable number.

21554157 is a deficient number, since it is larger than the sum of its proper divisors (7211283).

21554157 is a wasteful number, since it uses less digits than its factorization.

21554157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6643.

The product of its digits is 7000, while the sum is 30.

The square root of 21554157 is about 4642.6454742959. The cubic root of 21554157 is about 278.2981679152.

Adding to 21554157 its reverse (75145512), we get a palindrome (96699669).

The spelling of 21554157 in words is "twenty-one million, five hundred fifty-four thousand, one hundred fifty-seven".