21472749 has 16 divisors (see below), whose sum is σ = 32490240. Its totient is φ = 14009760.

The previous prime is 21472747. The next prime is 21472757. The reversal of 21472749 is 94727412.

It is not a de Polignac number, because 21472749 - 2¹ = 21472747 is a prime.

It is a super-2 number, since 2×21472749² = 922157899234002, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21472741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7192 + ... + 9729.

It is an arithmetic number, because the mean of its divisors is an integer number (2030640).

Almost surely, 2^21472749 is an apocalyptic number.

It is an amenable number.

21472749 is a deficient number, since it is larger than the sum of its proper divisors (11017491).

21472749 is a wasteful number, since it uses less digits than its factorization.

21472749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16977 (or 16971 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21472749 is about 4633.8697651099. The cubic root of 21472749 is about 277.9473573181.

The spelling of 21472749 in words is "twenty-one million, four hundred seventy-two thousand, seven hundred forty-nine".