21740157 has 20 divisors (see below), whose sum is σ = 32640960. Its totient is φ = 14419944.

The previous prime is 21740141. The next prime is 21740197. The reversal of 21740157 is 75104712.

It is not a de Polignac number, because 21740157 - 2⁴ = 21740141 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21740157.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21740137) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 18798 + ... + 19920.

It is an arithmetic number, because the mean of its divisors is an integer number (1632048).

Almost surely, 2^21740157 is an apocalyptic number.

21740157 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21740157 is a deficient number, since it is larger than the sum of its proper divisors (10900803).

21740157 is a wasteful number, since it uses less digits than its factorization.

21740157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1374 (or 1365 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 21740157 is about 4662.6341267571. The cubic root of 21740157 is about 279.0963940248.

Adding to 21740157 its reverse (75104712), we get a palindrome (96844869).

The spelling of 21740157 in words is "twenty-one million, seven hundred forty thousand, one hundred fifty-seven".